Middleby Marshall PS740G Operating instructions

SECTION 3 - SERVICING COMPONENTS
SECTION 3
SERVICING COMPONENTS
I.
CONVEYOR SPEED CONTROLLER AND DRIVE
MOTOR
A. Part Number Reference - Speed Controllers
1. Original-style speed controller with interchangeable microcomputer and thumbwheel. This unit is no longer
available and part numbers are provided for reference
only. Servicing this unit is beyond the scope of this
manual. If this controller is in need of service, we recommend simply installing a current unit (see below).
The Conveyor Speed Controller is used to set and monitor
the speed of the conveyor. The Controller consists of three
components:
•
Control Module
Early units used a module which featured a microcomputer that was unique to each oven model. Using this
control module required verifying that the correct microcomputer was installed.
P/N
28174-0004
28074-0006
27170-0232
28074-0007
28074-0008
27170-0233
28074-0013
Later units use DIP switches to set up the controller for
a particular oven model. This later model was initially
available with a thumbwheel unit (either 4 or 8 DIP
switches). Current models feature a digital display with
keypad (8 DIP switches).
•
2. Current-style speed controller with either 4 or 8 DIP switch
settings and thumbwheel. This unit is no longer available
from the factory, but may still be stocked by service agencies.
Thumbwheel Unit (or Digital Display with Keypad)
This module displays the conveyor speed and allows it
to be adjusted by the operator. It is connected to the
control module by a ribbon cable.
•
P/N
42810-0133
42810-0118
Pickup Assembly
The pickup assembly consists of a magnetic wheel on
the end of the gear motor (conveyor drive motor) shaft,
and a Hall Device sensor that provides feedback to the
control module.
Description
Controller assembly with thumbwheel
Thumbwheel only
3. Current-style speed controller with 8 DIP switch settings and digital display/keypad. Note that the two types
of controllers ARE NOT compatible - the controller and
display unit MUST be of the same type.
As the magnetic wheel turns, the revolutions of the
magnet are monitored by the Hall Device sensor. The
signals are sent to the control module, which compares
the motor speed with the speed shown on the
thumbwheel or digital display. The control module increases or decreases the voltage to the gear motor
(conveyor drive motor) depending on the signal.
P/N
37337
37503
45133
Figure 12
Original-style speed controller
Description
Controller assembly with digital display/keypad,
NCC (8/00-current)
Digital display/keypad unit only, NCC
Controller assembly with digital display/keypad,
Danaher (2/02-current)
Figure 13
Current-style speed controller
Produced with thumbwheel only.
Interchangeable microcomputer selects oven model.
THIS CONTROLLER IS OBSOLETE AND NO
LONGER AVAILABLE.
Control module
Description
PS360 controller, yellow (12A) microcomputer
PS360 microcomputer, yellow (12A)
PS360 microcomputer w/emulator, yellow (12A)
PS314 controller, orange (13A) microcomputer
PS314 microcomputer, orange (13A)
PS314 microcomputer w/emulator, orange (13A)
PS200 microcomputer, pink (15A)
Produced with Thumbwheel or digital display.
4 or 8 DIP switches select oven model.
DIP switches may
be on control
module or digital
display, depending
on the controller
model.
Microcomputer
Cover plate
shows DIP
switch settings
Thumbwheel
or digital
display
Control
module
Thumbwheel
13
SECTION 3 - SERVICING COMPONENTS
Figure 14
PS350-style pickup assembly
(used on early PS360)
B. Part Number Reference - Pickup Assemblies
1. PS350-style pickup assembly or old-style pickup assembly (see Figures 14-15). These parts use the same
part number. They are no longer available from the
factory, but may still be stocked by some service agencies.
P/N
28074-0005
Description
Pickup assembly, PS350-style or old-style
2. Current-style pickup assembly (see Figures 16-17)
P/N
27170-0263
Description
Pickup assembly, current
C. Preparing to Service the Speed Controller
NOTE: To properly service this equipment, you must use a
digital meter. An analog meter will not work.
1. Before troubleshooting the conveyor speed controller,
check the following:
a. Conveyor belt is tight.
b. Drive chain is tight and aligned.
c. Set screws on drive sprockets are tight.
Figure 15
Old-style pickup assembly
d. Axial fan(s) are running and clean of dust and debris.
e. Motor and pickup wires are secure at the Conveyor
Terminal Block (location of the block varies by oven
model).
f.
Wire connections on conveyor speed control module (including the ribbon cable to the thumbwheel/
display unit) are secure.
2. Check the pickup for the following (see Figures 14-17):
a. Pickup is secure.
b. Magnet is not cracked or chipped.
c. Magnet is not rubbing on plastic housing.
d. Mounting bolt is not worn or bent.
e. Pickup bearing in good condition.
f.
On PS350-style pickup (Fig. 14), gap between
magnet and Hall Device is spaced approximately
1/64”-1/32” (0.4-0.8mm, or a business card thickness).
14
SECTION 3 - SERVICING COMPONENTS
Figure 16
Current pickup assembly - side view
Figure 17
Current pickup assembly end view
Components needed for the field tester:
• Full-wave AC-DC bridge, 400V, 4A
• Light dimmer switch, 5A
• In-line 5A AC fuse enclosed in plastic case
• 2 alligator clips
D. Controller/Motor Failure
When the conveyor speed controller fails, it is very possible that a shorted conveyor motor caused the problem.
Unless the motor is changed, the installation of another
conveyor speed controller will simply burn up the new controller.
CAUTION: DO NOT turn the conveyor switch ON while
the field tester is connected!
You are STRONGLY ADVISED to bypass the speed controller and install the tester unit shown in Figure 18 before
replacing any speed controller that has burned out. This
will identify the source of the problem - the speed controller
or the motor. It is much less expensive to burn out the
tester than another speed controller.
1. Disconnect the motor lead wires and attach to the field
tester as shown in Figure 18. Depending on the oven
model, you can simply use the black and red gear motor
leads, or the remote leads at the terminal block connection.
The components for this tester can be purchased at any
electrical supply store. The tester is not as accurate or
sensitive as the speed controller, and so should NOT be
left in place on the oven after servicing!
To reverse the conveyor motor direction, simply interchange the black and red leads.
2. To start the test, the dimmer switch should be turned
until the motor begins to operate. The switch can then
be turned down to the desired motor speed.
Figure 18
Field Tester for Conveyor Drive Motor
or circuit breaker
15
SECTION 3 - SERVICING COMPONENTS
E. Basic Troubleshooting Flowcharts
1. IF THE GEAR MOTOR RUNS AT FULL SPEED:
NOTE:
Middleby no longer stocks parts for the original
speed controller with interchangeable microcomputer. If it is necessary to replace this version of
the controller or the microcomputer, and the
service agent does not have the parts in stock, it
will be necessary to replace the entire speed
controller with a current model.
16
SECTION 3 - SERVICING COMPONENTS
2. IF THE GEAR MOTOR WILL NOT RUN AT ALL:
NOTE:
Middleby no longer stocks parts for the
original speed controller with interchangeable microcomputer. If it is
necessary to replace this version of
the controller or the microcomputer,
and the service agent does not have
the parts in stock, it will be necessary
to replace the entire speed controller
with a current model.
17
SECTION 3 - SERVICING COMPONENTS
F. Initial Troubleshooting
3. With the AC power on,
check the DC voltage to
the conveyor motor.
Match the measured voltage with those shown on
the chart below. If the
voltage reading is more
than ±5VDC of that shown
on the chart, complete
the Motor Test on the next
page.
NOTE: When changing the conveyor speed on a controller
with a thumbwheel, it is advisable to turn the conveyor switch
OFF before adjusting the thumbwheel. Note that this cannot be done on a digital keypad, as switching the conveyor
switch OFF will also turn off the display.
1. Check all connections at the terminals on the conveyor
speed control module to ensure that they are correct
and tight. Connections are shown in the drawing.
Correct the connections if necessary.
Connections are
reversed if
conveyor direction is reversed.
Thumbwheel/
Display
Setting
120VAC supply.
Wire colors vary
by oven model.
3 mins.
4 mins.
5 mins.
6 mins.
7 mins.
8 mins.
9 mins.
10 mins.
11 mins.
12 mins.
13 mins.
15 mins.
2. Ensure that there is power to the controller. Use a
digital multimeter to read the voltage between the terminals marked “AC.” The voltage should read between
110-120VAC.
DC Motor Voltage
PS200,
PS310, 360,
570, 360WB70
360WB, 360EWB
84VDC
63VDC
51VDC
43VDC
37VDC
32VDC
29VDC
27VDC
24VDC
22VDC
19VDC
18VDC
67VDC
50VDC
40VDC
34VDC
28VDC
25VDC
22VDC
20VDC
18VDC
17VDC
14VDC
13VDC
4. Check the magnetic
pickup on the motor.
If the power is not present or of an incorrect voltage,
check the power source.
If the pickup is in good
condition, check that
the conveyor is running
and then check the voltage between the “COM
and “±5VDC” terminals
on the controller. On
controllers with thumbwheels, the voltage
should read 5VDC,
±0.3VDC. Digital controllers should read
5VDC , ±1.0VDC.
Next, check the voltage
between the “COM”
and “COUNT” terminals. The reading should stay between 2 and 3VDC.
If EITHER of these two readings are incorrect, perform
the Conveyor Control Pickup Test on the next page.
18
SECTION 3 - SERVICING COMPONENTS
G. Conveyor Control Pickup Test
H. Conveyor Motor Test
1. Visually check the pickup for the following:
• The magnet is clean and the bearing is in good
condition.
• There are no chips or cracks on the magnet.
• If using a PS350-style pickup (see Figure 14), there
is a 1/64” to 1/32” (0-4-0.8mm, or a business card
thickness) gap between magnet and hall device.
1. Disconnect the gear motor wires from the Speed Controller terminals (“-ARM” and “+ARM”).
2. Remove the brush retainer caps from the gear motor.
DO NOT remove the brushes.
3. Set the multimeter to the lowest Ohm scale. Then,
place one meter probe on each brush retaining plate.
BE SURE THAT NEITHER PROBE TOUCHES THE
MOTOR CASING.
4. Using a 5/16” open-end wrench, very slowly rotate the
motor pickup shaft while observing the multimeter. During a 1/2 rotation:
• The Ohm reading should stay betweeen 3-5W.
• There should NEVER be a complete short.
• There should never be a high Ohm reading.
If the motor fails any of these tests, replace the motor.
2
Set the multimeter to the VDC scale, then connect the
meter probes as shown in Figure 19. The black (-common) probe should connect to the “COM” terminal on
the speed control board, while the red (+VW) probe
connects to the “+5V” terminal. +5VDC should be
present at all times when the conveyor is operating.
•
•
If +5VDC is present, proceed to Step 3.
If +5VDC is not present, disconnect the three pickup
wires (connected to the “COM,” “SIGNAL,” and “+5V”
terminals) and again check for +5VDC.
- If +5VDC is present with the pickup disconnected, replace the pickup assembly.
- If +5VDC is still not present, replace the conveyor speed controller.
I.
Replacing the Magnetic Pickup
If you need to replace the magnetic pickup on a gear motor
shaft:
1. Apply Loctite Removable #242 (or equivalent) sparingly
to the threads.
2. Turn the mounting screw until it is finger tight, then turn
it an additional 1/4 turn with a wrench.
3. Connect the multimeter’s red (+) lead to the “SIGNAL”
terminal; then, disconnect the motor wires from the “ARM” and “+ARM” terminals. Using a 5/16” open-end
wrench, very slowly rotate the motor pickup shaft while
observing the multimeter. Two (2) changes from +5VDC
to 0VDC should occur for each motor revolution.
• lf the signal is always at 0VDC, go to Step 4.
• lf the signal is always at 5VDC, OR if the signal
changes more than 2 times per revolution, replace
the pickup assembly.
J. Unshielded Pickup Wires on Early PS360-series ovens
The conveyor speed controller can be affected by electrical
noise transmitted by other electrical components or wiring.
Early PS360-series ovens used an unshielded connection
between the pickup assembly and the control module. On
these ovens, the unshielded wiring can pick up the noise
and transmit it to the control module. The problem is most
easily seen when the conveyor fails during burner spark
ignition.
There are two remedies for this problem:
1. Turn the conveyor switch to the OFF position, and then
back to the ON position, after the burner has ignited.
The controller should reset and allow normal operation.
This should be used as a stop-gap measure ONLY to
allow the oven to continue operation.
2. Replace the pickup wiring between the control module
and the terminal block with a new shielded cable (P/N
42400-0334). When installing the shielded cable, follow the color code change shown here:
4. Disconnect the pickup signal wire from the speed controller and check for +5VDC at the “SIGNAL” terminal of
the controller.
• If +5VDC is present, replace the pickup assembly.
• If 0VDC is present, replace speed control.
Figure 19
Connections for pickup test
Old Wiring
Brown
Orange
Ye l l o w
19
Shielded Cable
Black
Red
White
Wiring diagrams are also provided in Figures 20 and 21
on the next page.
There is a fourth lead on one end of the shielded cable.
This is a ground lead which is attached to the black
wire of the cable. The ground lead should be connected
to the terminal block inside the motor compartment.
Current PS360-series ovens have the shielded cable
installed at the factory and do not require this retrofit.
SECTION 3 - SERVICING COMPONENTS
Figure 20
Wiring for PS360 Shielded
Pickup Cable - early terminal
block design
Figure 21
Wiring for PS360 Shielded
Pickup Cable - late terminal
block design
K. Appendices
Appendix - Conveyor sensor wiring changes for PS360-series and PS570S, 10/95
20
SECTION 3 - SERVICING COMPONENTS
Appendix - Service Bulletin MM-133B - Installation Instructions for Conveyor
Speed Controller Kit with Thumbwheel, P/N 42810-0133, 4/95
21
SECTION 3 - SERVICING COMPONENTS
Appendix - Service Bulletin MM-133B - Installation Instructions for Conveyor
Speed Controller Kit with Thumbwheel, P/N 42810-0133, 4/95
22
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 42810-0133Conveyor Speed Controller Kit with Thumbwheel, 4/95
23
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 42810-0133Conveyor Speed Controller Kit with Thumbwheel, 4/95
24
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 42810-0133Conveyor Speed Controller Kit with Thumbwheel, 4/95
25
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 42810-0133Conveyor Speed Controller Kit with Thumbwheel, 4/95
26
SECTION 3 - SERVICING COMPONENTS
Appendix - Service Bulletin MM-177 - Introduction and Compatibility of
Conveyor Speed Controller with Digital Display, P/N 37337, 8/00
Bulletin No. MM-177
Date:
8/18/00
Middleby Cooking Systems Group
1400 Toastmaster Drive • Elgin, IL 60120-9272 U. S. A. • Telephone: (847)741-3300 • Service and Parts Fax: (847)741-4406
Service Bulletin
SUBJECT
Availability of Conveyor Speed Controller Kits
GENERAL
Middleby Marshall is changing is standard Conveyor Speed Controller from the familiar thumbwheel
control to a unit that features a digital display with pushbutton speed selectors. The part numbers of
these components are summarized here:
Speed Controller with Thumbwheel
• Kit (includes control module and thumbwheel): 42810-0133
• Thumbwheel unit only: 42810-0118
Speed Controller with Digital Display
• Kit (includes control module and digital display): 37337
• Digital selector/display unit only: 37503
Because of this change, supplies of the previous speed controller are VERY LIMITED, and the separate thumbwheel is no longer available. Immediately stock the new Speed Controller units and save
your remaining thumbwheel controls for use with the oven models that cannot use the new controller.
APPLICATION
• Service agents should immediately begin to stock P/Ns 37337 and 37503 to fulfill their normal
need for conveyor speed controllers. The new units can be used without modification on ALL
OVENS EXCEPT THE PS200R68-SERIES.
•
Your existing stock of P/Ns 42810-0133 and 42810-0118 should be used, whenever possible,
ONLY for PS200R68-series ovens.
•
The new speed controller and digital display are already in use on Middleby Marshall PS555 ovens;
so, your Agency may already have some of these components in stock. Please check your existing stock of these components before placing addtional orders.
COMPATIBILITY
The Speed Controller with Digital Display is compatible with all Middleby Marshall ovens EXCEPT the
PS200R68, PS220R68, and PS224R68.
AVAILABILITY
• P/Ns 37337 and 37503 are available for immediate shipment.
•
P/N 42810-0133 is available in very limited quantities. Note that some future orders may not be
fulfilled.
•
P/N 42810-0118 is no longer available.
27
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 44756 - Conveyor Speed Controller Kit
for PS200R68-series Ovens, 2/02
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • USA • (847) 741-3300 • FAX (847) 741-4406
Instructions for Service Kit 44756
Conveyor Speed Controller Kit for PS200R68-series ovens
KIT COMPONENTS:
Qty.
P/N
1
37337
Description
Conveyor speed controller with digital display
1
44749
Cable assembly, PS200R68-series ovens
1
44757
Instructions, PS200R68-series oven conveyor speed controller kit
This Service Kit will update one Middleby Marshall PS200R68, PS220R68, or PS224R68 oven to operate using the current
digital conveyor speed controller with keypad display (P/N 37337), instead of the previous controller with thumbwheel
adjustment (P/N 42810-0133). If the oven is already equipped with controller P/N 37337, this Kit is not necessary; P/N 37337
may be used as a direct replacement for the existing controller.
WARNING
BEFORE PERFORMING ANY SERVICE WORK, THE ELECTRICAL POWER SUPPLY AND THE GAS
SUPPLY MUST BE TURNED OFF.
1.
Disconnect the oven from its electrical power supply at
the circuit breaker/fused disconnect. For gas ovens,
shut off the gas supply to the oven.
2.
Identify the 24-pin control cable (female at both ends) that
connects the rear of the remote box (on top of the oven) to
the rear of the machinery compartment (on the side of the
oven).
3.
Remove and discard the cable.
4.
Open the machinery compartment door and locate the
conveyor speed control module.
5.
One at a time, disconnect the leads from the terminals on
the existing speed control module and connect them to
the corresponding terminals on the new control module.
shown on the case of the controller and are also provided
in Figure 1.
9.
Install the new module in place. Close and fasten the
machinery compartment door.
10. Temporarily remove the remote box from the top of the
oven. Open the remote box.
11. Disconnect the thumbwheel unit’s ribbon cable plug from
its socket on the remote board. Then, remove and discard the thumbwheel unit.
12. Install the new digital display unit in place. Connect its
ribbon cable plug into its socket on the remote board.
13. Close the remote box and reinstall it atop the oven.
6.
Remove the ribbon cable plug from its socket on the old
speed control module, and attach it to the corresponding
socket on the new control module.
14. Install the new kit-supplied control cable between the back
of the remote box and the back of the machinery compartment.
7.
Remove and discard the old control module from the inside of the machinery compartment door.
15. Restore the electrical and gas utility supplies to the oven.
8.
Adjust the DIP switch settings on the new speed control
module to the correct settings for the PS200-series oven
with a 3-30 minute bake time range. These settings are
16. Test the operation of the new conveyor speed controller to
make certain that it is operating properly. The oven is now
ready for operation.
Figure 1
DIP Switch Settings
Middleby Cooking Systems Group
1400 Toastmaster Drive
Elgin, IL 60120
(847) 741-3300 • FAX (847) 741-4406
Middleby Corporation Service
Hotline 1-800-238-8444
P/N 44757 • Rev. C • V1 • 2/02
28
SECTION 3 - SERVICING COMPONENTS
Appendix - Service Bulletin MM-189 - New Conveyor Gear Motors,
Brushes, and Pickup Clamps, 8/01
Bulletin No. MM-189
Date:
8/24/01
Middleby Cooking Systems Group
1400 Toastmaster Drive • Elgin, IL 60120-9272 U. S. A. • Telephone: (847)741-3300 • Service and Parts Fax: (847)741-4406
Service Bulletin
SUBJECT
New conveyor gear motors, brushes, and pickup clamps for Middleby Marshall ovens
GENERAL
The conveyor gear motors used on all Middleby Marshall ovens (except model PS536) have been redesigned by the
vendor. Changes to the motors include:
•
A smaller-diameter motor casing.
•
New motor brushes.
Old-style motors continue to use brush P/Ns 22450-0052 or 22450-0230 as shown in the table below.
All of the new motors use brush P/N 46658.
-
•
A shorter clamp to attach the pickup assembly. This accommodates the smaller diameter of the motor.
The pickup assembly with the original clamp is still available as P/N 27170-0263. This kit is only available in
limited quantities. After our stock of the old-style pickup assembly kit is exhausted, you will need to save the
existing clamp to attach a new pickup assembly to an old-style motor.
The pickup assembly with the new, shorter clamp is available as P/N 46451.
All of the new motors will be shipped in a kit that also includes the new clamp. This allows you to attach an
existing pickup assembly to a new motor.
In 7/01 and 8/01, some of the new motors were shipped under the part numbers of the old motors. These parts
shipped without the new clamp. In most of these cases, you can tighten the existing clamp to fit the new motor.
Some older clamps, however, cannot be tightened enough to fit. To be sure that you can install the new motor
in all ovens, you should add the new clamp, P/N 46602, to your required parts stocking list, and carry a few
spare clamps on each service vehicle.
Please be aware of these changes as you order your stocking parts. Some versions of the old motor, as well as the oldstyle pickup assembly, are still available in limited quantities. The brush for the old motor (P/N 22450-0052) will remain
available in order to maintain motors already in the field.
Old
Motor
Old
Brush
Old
Pickup
New
Motor*
New
Brush
New
Pickup
New
Clamp
PS310
PS314
PS360/360S
PS360SS High Speed
PS360T Tandem
PS360WB
PS360WB70
PS360EWB
PS555
PS570/570S Single Belt
27384-0008
22450-0052
27170-0263
46603
46658
46451
46602
1350:1
PS200/220FS/224
PS200VL/220VL/224VL
PS200R68/220R68/224R68
PS200T Tandem
PS570/570S Split Belt (Standard)
27384-0011
22450-0230
27170-0263
46604
46658
46451
46602
600:1
PS314SBI
27384-0003
22450-0052
27170-0263
46605
46658
46451
46602
300:1
PS200/220FS/224 (High Speed)
27384-0014
PS570/570S Split Belt (High Speed)
22450-0230
27170-0263
46606
46658
46451
46602
Ratio
Used on
1400:1
* “New Motor” part numbers shown in this table are kits that include both the motor and the new pickup clamp.
29
SECTION 3 - SERVICING COMPONENTS
Appendix - DIP switch settings for Conveyor Speed Controller
with Digital Display (P/N 37337), 4/02
For this operating mode, the temperature controller is set
to the On-Off Mode as described in the Kit instructions.
II. TEMPERATURE CONTROLLER
The Temperature Controller is used to set and control the
oven temperature. Depending on the oven, model, the controller has several functions:
•
•
On gas ovens with On-Off gas valve operation, the temperature controller opens and closes the high flame
solenoid. This allows 100% or 0% gas flow to the burner
in response for the need for heat to maintain the set
point temperature. The temperature controller has no
effect on the low flame bypass or oven ignition.
For this operating mode, the temperature controller is set
to the PID Mode as described in the Kit instructions.
For this operating mode, the temperature controller is set
to the On-Off Mode as described in the Kit instructions.
•
Note that temperature controller P/N 46837
(inc. with Service Kit 47321) includes a dedicated variable pulse mode intended for the
PS536 electric oven. This special mode is NOT
used on the PS555.
On gas ovens with modulated gas valve (PID) operation, the temperature controller sends a signal to the
amplifier board which in turn controls the operation of
the modulating valve. This allows a modulated gas flow
of any necessary value from 0-100% in response for
the need for heat to maintain the set point. The temperature controller has no effect on oven ignition.
For this operating mode, the temperature controller is set
to the PID Mode as described in the Kit instructions.
•
On electric ovens with variable pulse heater activation
(including PS555 electric ovens), the temperature controller sends its signal to a controller module that contains an amplifier board and two solid state relays. The
relays activate the heating elements at 100% power on
a fixed cycle time, for a length of time proportional to
the signal from the temperature controller.
On electric ovens with On-Off heater activation (including most PS200-series and PS360-series electric ovens), the temperature controller permits or cuts power
to the heating elements as necessary to maintain the
set point temperature.
30
•
The temperature controller regulates the cooldown function. NOTE: PS200VL-series ovens do not include a
cooldown function.
•
On most PS200-series and PS300-series gas ovens
(except the PS200VL), the temperature controller monitors the high limit. All other oven models use a High
Limit Control Module that is independent of the temperature controller.
Middleby Marshall ovens have used several different models of temperature controllers. The current Digital Temperature Controller (P/N 46837, included in Service Kit 47321)
is the only model currently available. All other controllers
SECTION 3 - SERVICING COMPONENTS
shown are no longer available and part numbers are provided for reference only. Servicing these units is beyond
the scope of this manual. If one of these controllers is in
need of service, we recommend simply installing a current
unit (P/N 46837, included in Kit P/N 47321).
•
P/N 28071-0012 (A)
Analog Temperature Controller without high-limit and
cooldown functions, 120V, on-off mode only.
•
•
P/N 28071-0018 (A)
Analog Temperature Controller with high-limit and
cooldown functions, 120V, on-off mode only.
P/N 30871 (E)
Digital Temperature Controller with gray rubber face
plate and buttons with symbols, 208-240V, on-off mode
only. Used on early PS360WB70 and some CE oven
models.
•
P/N 32571 (E)
Digital Temperature Controller with gray rubber face
plate and buttons with symbols, 208-240V, PID mode
only. Used on early PS360EWB.
•
P/N 36021 (F)
Digital Temperature Controller with gray face plate (steel
trim on edges), 120-240V, selectable on-off or PID
modes.
A. Part Number Reference - Temperature Controllers
•
P/N 34983 (B)
Analog Temperature Controller without high-limit and
cooldown functions, 120V, on-off mode only. Used on
PS200VL-series ovens only. PS200VL-series ovens
equipped with this Temperature Controller do not have
a cooldown feature and use a separate high limit control module.
•
P/N 28071-0027 (C)
Digital Temperature Controller with blue plastic faceplate, 120V, on-off mode only.
•
P/N 36056 (G) - Service Kit P/N 36939
Digital Temperature Controller with black plastic face
plate, 120-240V, selectable on-off or PID modes.
•
P/N 28071-0028 (D)
Digital Temperature Controller with gray rubber faceplate and buttons with text, 120V, on-off mode only.
•
•
P/N 28071-0028 (E)
Digital Temperature Controller with gray rubber face
plate and buttons with symbols, 120V, on-off mode only.
P/N 46837 (G) - Service Kit P/N 47321
Digital Temperature Controller with black plastic face
plate, 120-240V, selectable on-off, PID and variable
pulse modes.
Note that the dedicated variable pulse mode is used on
the PS536 electric oven ONLY. Using this mode requires moving a jumper on one of the PC boards inside
the controller. The PS555 variable pulse electric oven
does NOT use this mode and should have the controller set to the PID mode as described in the Kit instructions.
Figure 22 - Temperature controllers
A
C
D
B
E
31
F
G
SECTION 3 - SERVICING COMPONENTS
D. Troubleshooting
1. Troubleshooting the Temperature Controller and
Thermocouple(s) using the Altek Thermocouple Source
(Middleby P/N 27170-0192)
• Turn the heat switch OFF.
• Disconnect the thermocouple leads from Terminals
7 and 8 on the temperature controller. Tape the
ends to prevent shorting.
• Connect the white lead of the Thermocouple Source
to Terminal 8 (+). Connect the red lead of the Thermocouple Source to Terminal 7 (-).
• Set the Thermocouple Source as close as possible to the customer’s set point. Then, turn the
BLOWER switch to the ON position.
The temperature controller should read close to the
customer’s set point. Failure indicates a problem with
the temperature controller. If the temperature controller is functioning properly, check the thermocouples.
Refer to Section IV, Thermocouples.
2. Troubleshooting the High Limit Switch
On ovens that use the high limit function of the temperature controller (most PS200-series and PS360-series ovens), an intermittent high limit switch will cause
intermittent operation of the burner. If you suspect that
this is a problem, a good check is to place a 1A fuse in
parallel around the switch contacts (terminals 11 and
12).
If the switch is functioning properly, the fuse will never
carry a load. The only time the switch would open
would be under a no-load condition.
If the switch is trying to open intermittently, however,
the full current load of the blowers will be carried by the
fuse. Regardless of the oven model, this load is far
greater than 1A, and the fuse will blow.
B. Description
The temperature controller consists of two main components: a sleeve or case (metal or plastic) with terminal connections on the back, and a plug-in chassis that includes
the faceplate and circuitry. The sleeve is mounted to the
panel or door of the oven, and the chassis is inserted into
the front of the sleeve.
VERY IMPORTANT: When replacing a controller, you
should ALWAYS replace the sleeve as well. Some controller models have sleeves of a similar size, but with DIFFERENT CONNECTIONS. Using an incorrect sleeve can damage the controller and cause the oven to function incorrectly. Exception: The sleeve used on Controllers 36056
and 46837 is identical except for the information label.
C. High Limit/Cooldown Functions
Except where noted in Section A (Part Number Reference),
the temperaturecontroller incorporates circuitry for the high
limit and cooldown functions.
1. The High Limit function (terminals 11 and 12) will shut
off the burner/heating elements if the oven temperature
sensed by the thermocouple(s) exceeds 650°F/343°C.
This function is used on most PS200-series and PS360series gas ovens. All other oven models use a separate high limit control module.
If the high limit temperature is reached, an indicator on
the controller will illuminate. The current controller
(P/N 46837) has a lamp marked “OVERTEMP” to show
this condition. Older controllers will have different indicators; you should refer to the operating instructions
for the controller in question for assistance.
2. The Cooldown function allows the blowers to continue
in operation after the operator switches off all operating
switches on the control panel. The blowers will remain
in operation until the cooldown switch opens (usually
180°F/82°C).
E. Appendices
Appendix - Temperature controller terminal cross-reference, 4/02
Terminal for
28071-0012 and
28071-0018
1
2
5
6
L2
L1
Terminal for
34983
TC+
TCCOM
NO
L2
L1
Terminal for
36056 and
46837
8
7
5
4
L2
L1
G
13
14
15
16
---
G
-------
9
10
11
12
15
16
Description
+ TC
- TC
Input to Temperature Control Relay
Output to High Flame Solenoid or Heater Contactors
Neutral
Power
Ground
Input to Cooldown Relay
Output from Cooldown Relay
Input to High Limit Relay
Output from High Limit Relay
PID or Variable Pulse Output
PID or Variable Pulse Output
32
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 47321 - Digital Temperature Controller Kit, 2/02
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • USA • (847) 741-3300 • FAX (847) 741-4406
Instructions for Service Kit 47321
Digital Temperature Controller
Installation, Programming and Troubleshooting Instructions
KIT COMPONENTS
Qty.
P/N
1
46837
1
47322
Description
Digital Temperature Controller (On/Off Gas & Electric, PID Gas, and
Variable Pulse Electric operating modes), with mounting brackets
Instructions
TABLE OF CONTENTS
Controller Types ............................................................................................... 2
Before You Begin ............................................................................................. 3
Installation ........................................................................................................ 3
Electrical Connections ..................................................................................... 4
Jumper Setting ................................................................................................. 6
Programming ................................................................................................... 6
Diagnostic Error Messages ............................................................................. 8
Operating Instructions (to be left with customer after installation) ...................... 9
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120
(847) 741-3300 • FAX (847) 741-4406
Middleby Corporation Service Hotline 1-800-238-8444
© 2002 Middleby Marshall.
Page 1 of 10
33
P/N 47322 • Rev. A • V2 • 2/02
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 47321 - Digital Temperature Controller Kit, 2/02
Controller Types
This Kit includes one Digital Temperature Controller (P/N 46837) that can operate at 120-240V, and
can be programmed to operate in on-off, PID, or variable pulse modes. The Controller is shown in
Figure 1G, below. By following these instructions, the Controller can be installed into any Middleby
Marshall oven equipped with the following Controllers.
•
P/N 28071-0012 (Fig. 1A)
Analog Temperature Controller without high-limit and
cooldown functions, operating at 120V, on-off mode only.
•
P/N 28071-0018 (Fig. 1A)
Analog Temperature Controller with high-limit and
cooldown functions, operating at 120V, on-off mode only.
•
P/N 34983 (Fig. 1B)
Analog Temperature Controller without high-limit and
cooldown functions, operating at 120V, on-off mode only.
Used on PS200VL models. As of 12/01, P/N 34983 is
still available and should be used on these ovens if
possible.
•
P/N 28071-0027 (Fig. 1C)
Digital Temperature Controller with blue plastic faceplate, operating at 120V, on-off mode only.
•
P/N 28071-0028 (Fig. 1D)
Digital Temperature Controller with gray rubber faceplate and buttons with text, operating at 120V, on-off
mode only.
•
P/N 28071-0028 (Fig. 1E)
Digital Temperature Controller with gray rubber face
plate and buttons with symbols, operating at 120V, onoff mode only.
•
P/N 30871 (Fig. 1E)
Digital Temperature Controller with gray rubber face
plate and buttons with symbols, operating at 208-240V,
on-off mode only. Used on early PS360WB70 and some
CE oven models.
•
P/N 32571 (Fig. 1E)
Digital Temperature Controller with gray rubber face
plate and buttons with symbols, operating at 208-240V,
PID mode only. Used on early PS360EWB.
•
P/N 36021 (Fig. 1F)
Digital Temperature Controller with gray face plate (steel
trim on edges), operating at 120-240V, selectable onoff or PID modes.
•
P/N 36056 (Fig. 1G)
Digital Temperature Controller with black plastic face
plate, operating at 120-240V, selectable on-off or PID
modes.
Figure 1
A
C
D
B
E
F
G
This Kit CANNOT be installed in a PS536 oven equipped with the P/N 44783 (variable pulse electric) or
P/N 44823 (PID gas) controller shown below.
H
Page 2 of 10
34
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 47321 - Digital Temperature Controller Kit, 2/02
WARNING
BEFORE PERFORMING ANY SERVICE WORK, THE ELECTRICAL POWER SUPPLY
AND THE GAS SUPPLY MUST BE TURNED OFF.
Before you Begin
1. This Temperature Controller requires a current-version thermocouple for proper operation. Check
that the thermocouple(s) installed in the oven match the current three-lead, flanged versions BEFORE you begin to install the Temperature Controller. See Figure 2.
If the oven is not equipped with current thermocouples, you should replace them BEFORE you install
the new Temperature Controller.
P/N 33984: Thermocouple kit for PS300-series, PS555 and PS570
P/N 33985: Thermocouple kit for PS200-series and PS536
Figure 2
Cable
(3 leads)
flange
Current thermocouple
Cable
(2 leads)
Obsolete 2-lead
thermocouple
Installation
clip
1. Check the oven’s existing temperature controller, as shown on the previous page.
• IF THE EXISTING CONTROLLER IS P/N 36056 OR P/N 46837 (shown in Figure 1G), the new
controller can be installed directly into the existing sleeve as follows:
- Loosen the Phillips screw at the bottom center of the faceplate.
- Pull the old controller out of the sleeve.
- Skip ahead to the Jumper Setting section of these instructions on Page 6 to set up the new
controller. After the jumper is configured, the new controller can be installed directly into the
existing sleeve.
• IF THE EXISTING CONTROLLER IS OF ANY OTHER TYPE, the sleeve will have to be replaced
with the one included in this Kit. Continue on to Step 2 in this section.
2. Access the back of the existing temperature controller. Tag each wire that connects to the controller
with its terminal number. These numbers will be used later to wire the new controller.
3. Disconnect all wires from the terminals on the temperature controller. Be sure to retain any jumpers
that are removed.
4. Remove the controller and sleeve from the oven as follows:
• For analog controllers P/Ns 28071-0012 and 28071-0018 (Fig. 1A), remove the two bracket
screws on the back of the control. Then, remove the bracket. Pull the controller and sleeve out
through the front of the oven panel.
• For all other controllers, remove the two screws and brackets that hold the controller in place.
Then, pull the controller and sleeve out through the front of the panel.
Page 3 of 10
35
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 47321 - Digital Temperature Controller Kit, 2/02
5. Check that the new controller is mounted into its sleeve. Then, slide the assembly into the opening in
the panel from the outside. Check that the controller is upright, with the display on top and the
keypad on the bottom.
6. Locate the rectangular holes on the top and bottom of the new controller’s sleeve. Attach the two kitsupplied mounting brackets against the inside panel of the oven, and into the holes in the sleeve, as
shown in Figure 3. Check that the heads of the screws point to the rear of the controller.
7. Tighten the two screws evenly until the lip of the sleeve is seated tightly against the panel.
8. If there is a protective clear plastic strip on top of the display, remove it at this time.
Figure 3
Temperature controller is
pre-installed into sleeve
and is upright
Control
panel
Bracket clips and
screw heads point to
REAR of controller
Electrical Connections
1. Wire the new controller as follows:
• If you are replacing an Analog Temperature Controller, P/Ns 28071-0012 or 28071-0018 (see
Fig. 1A), refer to Figure 4A for a listing of the new terminal numbers.
• If you are replacing an Analog Temperature Controller P/N 34983 (Fig. 1B - PS200VL models
only), refer to Figure 4B for a listing of the new terminal numbers.
• If you are replacing any Digital Temperature Controller, simply reconnect ALL of the original
wires and jumpers to the same terminals, as all terminals are numbered the same.
EXCEPTION: Controller P/N 32571(Fig. 1E - used on early PS360EWB ovens only) uses Terminals 4 & 5 for the mA output to the amplifier board. The current controller uses Terminals 15 & 16 for
these connections, as shown in Figure 5A.
Page 4 of 10
36
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 47321 - Digital Temperature Controller Kit, 2/02
Figure 4a
Figure 4b
Analog temperature controller (P/Ns
28071-0012 and 28071-0018) terminals
Analog temperature controller
(P/N 34983) terminals
New temperature
controller terminals
New temperature
controller terminals
Not used on
some gas and
electric ovens
Not used
Not used. PS200VL
ovens have a separate high limit module
and do not include a
cooldown feature.
Not used
Not used
Not used
Not used. PS200VL
ovens do not include a
modulating gas system.
Not used. These
terminals provide PID
output (gas ovens
with
modulating
valve) or variable
pulse output (electric ovens with
variable pulse system). Neither of
these systems were available with
ovens equipped with these
controllers.
Terminal for
28071-0012 and
28071-0018
1
2
5
6
L2
L1
G
13
14
15
16
---
Terminal for
34983
TC+
TCCOM
NO
L2
L1
G
-------
Terminal for
46837
8
7
5
4
L2
L1
9
10
11
12
15
16
Description
+ TC
- TC
Input to Temperature Control Relay
Output to High Flame Solenoid or Heater Contactors
Neutral
Power
Ground
Input to Cooldown Relay
Output from Cooldown Relay
Input to High Limit Relay
Output from High Limit Relay
PID or Variable Pulse Output
PID or Variable Pulse Output
Figure 5a
Modulated Gas Output System
4-20mA
input
Amplifier board
Figure 5b
Modulating
valve
Variable Pulse Output System
Relay
20VDC pulsed output
0-24VDC
output
NOTE: Controller P/N 32571 used Terminals 4 & 5
for the 4-20mA input to the amplifier board.
These connections must be moved to Terminals
15 & 16 on the new controller as shown.
24VAC
input
Page 5 of 10
37
NOTE: Safety switches
may be placed between
the temperature controller
and the relay on some
oven models.
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 47321 - Digital Temperature Controller Kit, 2/02
Jumper Setting
Loosen the Phillips screw at the bottom center of the faceplate. Then, pull the controller out of its sleeve.
Next, access the jumper shown in Figure 6. This jumper affects the signal that is output from Terminals
15 and 16. The jumper MUST be set to the correct position for proper operation of the controller.
CAUTION
If the jumper is incorrectly set, the oven will be unable to properly maintain temperature. In addition, DAMAGE MAY OCCUR TO THE CONTROLLER AND OTHER OVEN COMPONENTS.
Always make sure that the jumper is correctly set BEFORE restoring power to the oven!
•
For gas ovens equipped with the modulating gas system, the jumper must be set to the
“W1” position.
This instructs the controller to send a variable-current 4-20 mA signal from Terminals 15 and 16 to
the amplifier board. The board converts this to a 0-24VDC signal which is sent to the modulating
valve. The valve regulates the gas flow according to the need for heat to maintain the set point.
For gas ovens, you should always check inside the machinery compartment to see whether a modulating valve is present in the unit before setting this jumper.
• For electric ovens equipped with the variable pulse system, the jumper must be set to the
“W2” position.
This instructs the controller to send a constant-current, pulsed 20VDC signal to the relay. Once per
second, the signal “pulses” on proportional to the need for heat to maintain the set point.
As of 1/02, only the PS536 Electric oven uses the variable pulse system. Other oven models equipped
with this system will be announced by Middleby as they become available.
• For all other ovens - gas or electric - that use the on-off system, the jumper may be set to
either position.
After the jumper has been properly set, replace the controller into its sleeve and tighten the screw.
Figure 6
Jumper is set to the “W1”
position for gas ovens with
modulating gas system
Jumper is set to the “W2”
position for electric ovens
with variable pulse system
Programming
1. Restore electrical power to the oven.
2. Refer to Figure 7. Set the following options,
according to the customer’s preferences:
• Set Point locked or unlocked
• Degrees Fahrenheit or Celsius
• Set Point or Actual Temperature display
3. Set the controller to PID or On-Off operating
mode. Choose the PID mode for BOTH gas
ovens with the modulating system AND for electric ovens with the variable pulse system.
4. Adjust the Set Point according to the
customer’s specifications.
5. If the PID operating mode was chosen, perform an Auto-Tune calibration as per the instructions in Figure 7.
6. Check that the customer is familiar with the
operation of the controller. The last page of
these instructions includes an operating guide
for the controller. Remove this page and leave
it with the customer for future reference.
Page 6 of 10
38
SECTION 3 - SERVICING COMPONENTS
Figure 7
Temperature Controller Service Instructions
Appendix - Instructions for Service Kit 47321 - Digital Temperature Controller Kit, 2/02
Page 7 of 10
39
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 47321 - Digital Temperature Controller Kit, 2/02
Diagnostic Error Messages
The controller runs background tests during normal operation. If any problems occur during the tests, an
error message flashes in the display. A listing of these diagnostic error messages is shown below.
Flashes on the display (alternating with the temperature)
indicating that the internal diagnostic test has failed.
The oven temperature has
not reached 200°F/93°C
within 15 minutes of startup.
On gas ovens, this is usually
a result of the burner not lighting.
Caused by an open in the
thermocouple circuit.
Polarity of the thermocouple
leads is reversed.
1. Turn the Blower Switch (HEAT Switch for PS536 ovens with the twoswitch configuration) OFF for 2 minutes.
2. Turn the Blower Switch (or HEAT Switch, as per Step 1) ON.
3. If necessary, repeat Steps 1 and 2 up to two additional times.
4. If the problem does not clear after 3 attempts, replace the controller.
1. Turn the Blower Switch (HEAT Switch for PS536 ovens with the twoswitch configuration) OFF for 2 minutes.
2. Turn the Blower Switch (or HEAT Switch, as per Step 1) ON.
3. If the problem does not clear, contact the Middleby Technical Service Department for assistance.
1. Check that the thermocouple leads are properly connected to Terminals 7 & 8 of the temperature controller.
2. Check the continuity of the thermocouple at room temperature. You
should measure 9-20 Ohms of resistance.
3. If the reading was outside the correct range, the thermocouple has
an open. Remove and replace the thermocouple.
If the reading was inside the correct range, contact the Middleby
Technical Service Department for assistance.
1. Check the polarity of the thermocouple leads. The red wire (-) should
be attached to Terminal 7 on the temperature controller. The white
wire (+) should be attached to Terminal 8.
2. If the polarity connections are incorrect, connect the thermocouple
properly.
If the polarity connections are correct, replace the thermocouple.
Page 8 of 10
40
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 47321 - Digital Temperature Controller Kit, 2/02
Digital Temperature Controller
P/N 46837
Operating Instructions
"SP LOCK" Light
Lights when the set
point is locked out
from changes. This
setting can only be
changed by service
personnel.
Display
Shows the Set Point or
the Actual Temperature in degrees Fahrenheit (F) or Celsius
(C).
"HEAT ON" Light
Lights when the
burner or heating elements, as appropriate
for the oven model,
are in operation.
"SET PT" (setpoint)
Light
Lights when the set
point is shown in the
display.
"ACTUAL TEMP"
Light
Lights when the
Actual Temperature is shown in
the display.
OVERTEMP Light
Lights when the oven
temperature is greater
than 650°F (343°C).
Temperature Key
Press this key once to
view the Actual Temperature in the Display.
Unlock Key
Press this key together
with the Set Point Key
to allow the Set Point
to be changed. Changes
can only be made for
60 seconds.
Service Key
For use by service personnel
only.
Up Arrow and Down Arrow
Keys
Press these keys to adjust
the Set Point up or down. If
the Set Point will not
change, refer to Set Point
Key and Unlock Key.
41
Set Point Key
Press this key together
with the Unlock Key to
allow the Set Point to
be changed.
Changes can only be
made for 60 seconds.
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 47321 - Digital Temperature Controller Kit, 2/02
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120
(847) 741-3300 • FAX (847) 741-4406
Middleby Corporation Service Hotline 1-800-238-8444
42
SECTION 3 - SERVICING COMPONENTS
Appendix - Service Bulletin MM-136 - Electrical Noise
Filter Capacitor Assembly on Temperature Controllers, 9/93
43
SECTION 3 - SERVICING COMPONENTS
Appendix - Service Bulletin MM-136 - Electrical Noise
Filter Capacitor Assembly on Temperature Controllers, 9/93
44
SECTION 3 - SERVICING COMPONENTS
III. HIGH LIMIT CONTROL MODULE
C. Operation and Troubleshooting
On most PS200-series and PS300-series gas ovens, the
temperature controller monitors the high limit. All other
oven models use a High Limit Control Module that is independent of the temperature controller.
Refer to the wiring diagrams at the back of this manual for
high limit wiring connections.
The Watlow high limit control module generally uses a dedicated high limit thermocouple. Some older ovens use a
dual-function, four-lead thermocouple that sends a signal
to both the temperature controller and the high limit control
module. Refer to Thermocouples on Page 54 for details.
Middleby ovens have used several different types of high
limit control modules. See Figure 23.
•
The United Electric Type 54 control was used for high
limit functions only. Ovens equipped with this control
did not have a cooldown feature. The control was used
on early PS310 and PS360 electric ovens.
•
The United Electric Type 55 control included both high
limit and cooldown functions, and was used on PS310
and PS360 electric ovens.
•
The Watlow high limit control module is the only version still in use by Middleby. The module includes
high limit functions only. The cooldown function is controlled by the oven’s temperature controller, except on
PS200VL-series ovens, which do not include a
cooldown feature.
The Watlow high limit control module is used on PS200series, PS360-series, and PS555/570-series ovens.
If the temperature sensed by the high limit thermocouple
exceeds 650°F/343°C, the high limit control module will
shut down the oven and illuminate the green reset button.
The module will need to be reset (by pressing the reset
button) before the oven can be operated. The reset button
is located inside the machinery compartment to ensure that
it is reset by an authorized service agent. The agent should
determine and correct the cause of the high limit condition
before returning the oven to service.
An open high limit thermocouple will trigger the high limit
control module to shut down the burner. The high limit
control will need to be reset after the open is corrected (as
per the procedure described above) before the oven can
return to operation.
Service information in this Manual is limited to the current
Watlow high limit control module. The United Electric units
are no longer available. Service Kit P/N 39733 can be used
to upgrade either of the two previous controllers to the
Watlow version.
Figure 23 - High limit control modules
(Shown in PS360-series oven)
United Electric Type 54
high limit control module
A. Part Number Reference - High Limit Control Modules
P/N
Description
28071-0002
United Electric Type 54 high limit control module
No longer available - upgrade to current model
34982 using Service Kit 39733
28071-0014
United Electric Type 55 high limit/cooldown control module
No longer available - upgrade to current model
34982 using Service Kit 39733
34982
Watlow high limit control module, 115V
For use on ovens with 120V control circuits
33983
Watlow high limit control module, 240V
For use on ovens with 208-240V control circuits
30693
Illuminated reset button (green) for Watlow control (all voltages)
39733
High Limit Conversion Kit for PS300, PS310,
PS350, and PS360 ovens
Replaces P/Ns 28071-0002 or 28071-0014 with
P/N 34982
United Electric Type 55
high limit/cooldown
control module
B. Location
On ovens that include the separate high limit control module, it is located:
• PS200-series - Inside the machinery compartment.
• PS360-series - Inside the control compartment.
• Early PS555 ovens - Inside the left blower motor compartment.
• Current PS555 and all PS570 ovens - Inside the
machinery compartment.
Watlow high limit
control module
Reset button
45
SECTION 3 - SERVICING COMPONENTS
D. Appendices
Appendix - Instructions for Service Kit 39733 High Limit Conversion Kit for PS300, 310, 350 & 360 Ovens, 5/99
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • USA • (847) 741-3300 • FAX (847) 741-4406
Instructions for Service Kit 39733
High Limit Conversion Kit for PS300, 310, 350, & 360 Ovens
KIT COMPONENTS - Check that the kit includes ALL of these parts BEFORE you begin!
Qty.
P/N
1
1
1
1
1
39732
34982
30693
35634
35691
1
1
33812-1
39690
Description
Instructions
Watlow high limit control module
Reset switch w/ lighted pushbutton
Mounting bracket, reset switch
Wire set, reset switch (includes 4
wires and 3 1/4”/25mm connectors)
Thermocouple, type J, 6”/152.4mm
Mounting sleeve, thermocouple
Qty.
P/N
2 ft./610mm
2 ft./610mm
2 ft./610mm
8
1
2
2
4
27152-0050
27152-0053
27152-0054
1455A8750
3002693
2000076
1421B8803
2001327
TOOLS REQUIRED
•
•
•
Drill with 3/16” drill bit
Middleby Marshall Thermocouple Signal Source
Generator (P/N 27170-0192)
Wire cutters/strippers
Description
Wire, #18 AWG, brown
Wire, #18 AWG, white
Wire, #18 AWG, purple
Wire connector, 1/4”/6.4mm
Wire tie, nylon
Screw, 6-32 X 1-5/8”
Screw, 6-32 X 1/4”
Nut, 6-32
Figure 1
United Electric Type 54
High Limit Control
A. OVERVIEW
This Service Kit is used to replace two different types of
United Electric high limit/cooldown controllers with a
Watlow high limit controller for PS300, 310, 350, and
360 Ovens. See Figure 1.
•
The early (Type 54) United Electric control was ONLY
equipped with a high limit circuit. Ovens equipped
with this control did NOT have a cooldown circuit.
This control was used on the following models:
-
PS300/350 Gas (early)
PS300/310/350/360 Electric (early - all voltages)
United Electric Type 55
High Limit/Cooldown
Control
For these ovens, the kit directly replaces the Type
54 high limit control with the Watlow high limit control.
•
The later (Type 55) United Electric control was
equipped with BOTH high limit and cooldown circuits,
and was used on the following models:
-
PS300/310/350/360 Electric (late), 208/240V and
480V UL versions ONLY
For these ovens, the kit replaces the Type 55 control with the Watlow high limit control, and uses the
oven’s temperature controller to provide the
cooldown circuit.
Page 1 of 8
46
Lighted Reset
Switch
Watlow High
Limit Control
P/N 39732
Rev. B • V1 • 5/99
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 39733 High Limit Conversion Kit for PS300, 310, 350 & 360 Ovens, 5/99
B. INSTALLATION
WARNING
BEFORE PERFORMING ANY SERVICE WORK, THE GAS SUPPLY (IF SO EQUIPPED) AND
THE ELECTRICAL SUPPLY TO THE OVEN MUST BE TURNED OFF.
1. Open the machinery compartment and control compartment access panels.
2. Locate the high limit thermo bulb/capillary assembly. Its location is shown in Figure 2. Loosen the set
screw that holds the assembly in place. Remove the thermo bulb/capillary assembly from the mounting tube.
3. Disconnect the wires (2 for the Type 54 control, 4 for the Type 55 control) from the terminals of the
United Electric control. Bundle the loose wires together, and allow them to hang loose for later
reconnection.
4. Remove the mounting screws that hold the United Electric high limit control in place. Then, remove
and discard the high limit control and its mounting screws.
5. Position the new high limit control in place on the left wall of the control compartment, as shown in
Figure 3. When positioning the control:
•
•
Ensure that the control is positioned AT LEAST 1” (25mm) back into the compartment to allow the
compartment door to close.
Ensure that additional space is left underneath the control for the reset switch.
NOTE: Instead of holding the high limit control in place, you may use the dimensions provided in
Figure 4 to determine the location of the control and its mounting holes.
6. Mark the locations of the two mounting holes for the high limit control. Then, drill the holes using a
3/16” drill bit.
7. Secure the high limit control in place using the kit-supplied 6-32 x 1-5/8” screws and 6-32 nuts.
8. Position the bracket for the reset switch on the left wall of the control compartment, as shown in Figure
3. Note that the face of the bracket with the large, circular switch-mounting hole should face YOU.
Also, the bracket should be positioned AT LEAST 3” (75mm) back into the compartment to allow the
door to close.
9. While holding the bracket in place, mark the locations of the two mounting holes. Then, remove the
bracket and drill the holes using a 3/16” drill bit.
10. Secure the bracket to the panel using the kit-supplied 6-32 x 1/4” screws and 6-32 nuts. DO NOT
INSTALL THE RESET SWITCH INTO THE BRACKET AT THIS TIME.
11. Insert the kit-supplied thermocouple into its mounting sleeve. Position the sleeve so that the mounting
hole is at the base of the thermocouple, not the tip. See Figure 5.
12. Insert the thermocouple and mounting sleeve into the original mounting tube. The set screw opening
in the sleeve should align with the set screw hole on the side of the mounting tube.
Push the thermocouple into the opening until its base seats firmly on the mount. See Figure 6.
13. Insert the thermocouple’s set screw into the hole on the side of the mounting tube. Tighten the set
screw to hold the thermocouple and sleeve in place.
14. Thread the thermocouple’s shielded cable into the electrical compartment. Coil the free end of the
cable and fasten it with the kit-supplied nylon wire tie. Be sure to leave enough free cable to reach the
new high limit control.
Page 2 of 8
47
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 39733 High Limit Conversion Kit for PS300, 310, 350 & 360 Ovens, 5/99
Figure 2
High limit thermocouple location lower oven
High limit thermocouple location upper oven
Figure 3
Figure 4
NOT TO SCALE
Figure 5
Figure 6
Thermocouple
Base
Sleeve
Hole in sleeve is
next to base of
thermocouple
Page 3 of 8
48
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 39733 High Limit Conversion Kit for PS300, 310, 350 & 360 Ovens, 5/99
C. WIRING
For the various wiring connections listed below, cut the kit-supplied #18 AWG wires to length. Refer to
Figures 7 and 8 (on pages 6 and 7) for diagrams of the wiring connections.
Lighted Reset Switch Wiring and Installation
14. Using the kit-supplied 1/4” wire connectors, connect the following kit-supplied wires:
-
Red wires ................. connect one wire to each “RESET” terminal on the high limit control
Black wire ................. connect to terminal “NC” on the high limit control
White wire ................. connect to terminal “L2” on the oven’s temperature controller
15. Slip the free ends of these four wires through the circular hole in the reset switch mounting bracket, so
that they hang down in front of the control compartment.
16. Use the kit-supplied 1/4” wire connectors to connect these four wires to the terminals on the lighted
reset switch.
-
Terminals 1 and 3 ..... Red wires (these connections are interchangeable)
Terminal 2 ................ Black wire
Terminal 4 ................ White wire (kit-supplied)
17. Push the lighted reset switch through the mounting hole in the center of the bracket until it snaps into
place. Be sure to avoid pinching the wires against the sides of the mounting hole.
Cooldown circuit wiring
NOTE: Perform steps 18 and 19 ONLY if you are replacing a UE Type 55 controller. If you are
replacing a UE Type 54 controller (which has no cooldown circuit), skip ahead to Step 20.
18. Attach the oven’s existing cooldown wiring to the following terminals on the oven’s Temperature Controller, as shown in Figures 7 and 8.
For Ovens with a Digital Temperature Controller:
a. Terminal 9 ................ Black wire (from blower switch)
b. Terminal 10 .............. Brown wire (from blower switch)
For Ovens with an Analog Temperature Controller:
a. Terminal 13 .............. Black wire (from blower switch)
b. Terminal 14 .............. Brown wire (from blower switch)
19. Attach a brown kit-supplied wire between the following terminals on the Temperature Controller:
Digital Controller ............. Terminals 10 and “L1”
Analog Controller............ Terminals 13 and “L1”
High Limit Control wiring
20. Using the kit-supplied 1/4” wire connectors, wire the high limit control terminals as follows:
a.
c.
d.
f.
h.
Terminal “NO” ...........
Terminal “TC +” ........
Terminal “TC -” .........
Terminal “L2” ............
Terminal “COM” ........
Purple wire (originally to UE control)
White wire (to thermocouple) - DO NOT CUT THIS WIRE TO LENGTH.
Red wire (to thermocouple) - DO NOT CUT THIS WIRE TO LENGTH.
White wire (kit-supplied; to neutral on the oven’s terminal block)
Orange wire (originally to UE control)
21. Using a 1/4” wire connector, attach a brown kit-supplied wire to the “L1” terminal on the high limit
control. Attach the free end of the wire to the “L1” terminal on the temperature controller.
Page 4 of 8
49
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 39733 High Limit Conversion Kit for PS300, 310, 350 & 360 Ovens, 5/99
D. TESTING THE INSTALLATION
22. Remove the thermocouple wires from the “TC +” and “TC -” terminals on the high limit control.
23. Attach a Middleby Marshall Thermocouple Source (P/N 27170-0263) to the “TC +” and “TC -” terminals on the high limit control, in place of the thermocouple wires. Note that it may be necessary to
attach a pair of terminal connectors to the leads of the Thermocouple Source to allow them to connect
to the high limit control’s terminals.
24. Restore the gas supply (if so equipped) and the electrical supply to the oven. Because the control
compartment door is still open, pull the door safety switch out into the “service” position.
25. Test the operation of the high limit control as follows:
a. Set the Thermocouple Source to a normal operating temperature, between 200°-600°F (93°-315°C).
b. Turn the oven on, and allow it to heat to 600°F (315°C).
c. After the oven has reached the setpoint temperature, set the Thermocouple Source to 700°F (371°C).
The high limit control is set to open at any temperature in excess of 650°F (343°C). This will shut
down the oven’s heat circuit and illuminate the Reset Switch lamp.
26. Set the Thermocouple Source to a temperature setting below 600°F (316°C), and depress the Reset
Switch. This should turn off the Reset Switch lamp and restore heat circuit operation.
27. Turn the oven off.
28. If you replaced a UE type 55 controller (with a cooldown circuit), you must set the Thermocouple
Source to a temperature setting below 200°F (93°C). Then, wait for the blowers to turn off.
29. Press the door safety switch in to reset it to normal.
30. Remove the Thermocouple Source from the oven.
31. Reattach the thermocouple wires to the high limit control’s terminals as follows:
White wire ................ “TC +”
Red wire ................... “TC -”
32. Close the machinery compartment and control compartment access panels, and fasten them in place.
The oven is now ready for normal operation.
Page 5 of 8
50
SECTION 3 - SERVICING COMPONENTS
KEY
Figure 7 - United Electric Model 55 replacement: ovens with a cooldown feature
Appendix - Instructions for Service Kit 39733 High Limit Conversion Kit for PS300, 310, 350 & 360 Ovens, 5/99
Page 6 of 8
51
SECTION 3 - SERVICING COMPONENTS
KEY
Figure 8 - United Electric Model 54 replacement: ovens without a cooldown feature
Appendix - Instructions for Service Kit 39733 High Limit Conversion Kit for PS300, 310, 350 & 360 Ovens, 5/99
Page 7 of 8
52
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 39733 High Limit Conversion Kit for PS300, 310, 350 & 360 Ovens, 5/99
A MIDDLEBY COMPANY
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • USA • (847) 741-3300 • FAX (847) 741-4406
Middleby Corporation Service Hotline 1-800-238-8444
www.middleby.com
Page 8 of 8
53
SECTION 3 - SERVICING COMPONENTS
Figure 24 - Thermocouples
IV. THERMOCOUPLES
All temperature controller and high limit functions are based
on input from thermocouples. When two wires composed
of dissimilar metals are joined together and one of the ends
is heated, a continuous current flow is generated. Middleby
ovens use a Type J (iron constant) thermocouple. The iron
wire increases the number of dissimilar metal junctions in
the circuit.
Middleby has used several types of thermocouples. All
can be replaced with the current version. Refer to Figure
24 for illustrations.
• A two-lead thermocouple with a small retaining clip.
Used for EITHER temperature-sensing OR high-limit
functions. This type is no longer available.
• A four-lead thermocouple with a small retaining clip.
This is a dual-function unit that sends its signal to the
temperature controller and to a separate high limit control module. This type is no longer available.
• A three-lead thermocouple with a separate ground lead,
a shielded cable and a large mounting flange. This is
the only type of thermocouple available from Middleby
at this time. If it is used to replace a four-lead dualfunction thermocouple, two complete and separate thermocouples will have to be installed.
Current 3-lead
thermocouple
Obsolete 2-lead
or 4-lead
thermocouple
Cable
(2 or 4 leads)
clip
A. Part Number Reference - Thermocouples
Part numbers are provided ONLY for the current, 3-lead thermocouple kits. These thermocouples include instructions
for replacing all previous thermocouple designs, in all oven
models.
P/N
Description
33984 Kit, thermocouple, PS360-series or PS555/570
series
33985 Kit, thermocouple, PS200-series or PS536
B. Thermocouple Functions
1. Temperature-sensing thermocouple(s)
All thermocouples monitor oven temperature. However,
Middleby uses the term “temperature-sensing thermocouple” in reference to thermocouples that send their
signal to the temperature controller instead of to a separate high limit control module.
On ovens that do NOT include a separate high-limit
control module (this includes most PS200-series and
PS360-series gas ovens), this thermocouple signal is
used to monitor the oven temperature for regulating the
gas flow/heater activation, AND to activate the high limit
warning in case of an overtemp condition.
Middleby ovens use from one to three temperature-sensing thermocouples, depending on the oven model.
Temperature-sensing thermocouples are used on all
oven models and are connected to Terminals 7 and 8
on the temperature controller. Based on the signal from
this thermocouple, the temperature controller:
• Calls for heat from the burner/heating elements to
maintain the set point (output from Terminals 4 & 5
for on-off electric and gas ovens; output from Terminals 15 & 16 for variable pulse electric and modulating gas ovens).
• Controls the cooldown feature if the HEAT switch
is turned off while the oven is above the cooldown
temperature (output from Terminals 9 & 10).
• On ovens without a separate high limit control module (most PS200-series and PS360-series gas and
electric ovens), the oven temperature sensed by
this thermocouple is also used to activate the high
limit warning (output from Terminals 11 & 12).
Cable
(3 leads)
flange
2. High limit thermocouple
Middleby uses the term “high limit thermocouple” in
reference to the thermocouple that sends its signal
solely to the separate high limit control module.
If the oven does not have a separate high limit control
module, there is no high limit thermocouple. On these
ovens, the temperature-sensing thermocouple(s) control high limit activation.
C. Troubleshooting
1. Open thermocouple
An open in a thermocouple will cause the temperature
controller to read the maximum temperature (usually
909°F/487°C). This causes the following:
• On ovens without a separate high limit control module, an open thermocouple triggers the high limit
alarm. This shuts down the burner. After the open
has been corrected, the high limit will need to be
reset to allow the oven to resume operation.
• On ovens with a separate high limit control module, an open temperature-sensing thermocouple
causes the temperature controller to stop calling
for heat. This shuts down the burner.
• On ovens with a separate high limit control module, an open high limit thermocouple will trigger the
high limit control module to shut down the burner.
Note that the high limit control will need to be reset
after the open is corrected before the oven can return to operation.
54
SECTION 3 - SERVICING COMPONENTS
2. Checking the thermocouple with a DC millivolt meter
It is possible to check that a thermocouple is reading
accurately by using a multimeter set to read DC millivolts. At 32°F/0°C the thermocouple should read
0 mVDC. This can be checked by inserting the ther-
mocouple into an ice bath for several minutes. At 72°F/
22°C the reading should be 1.134mVDC.
You can use the chart below by checking the temperature at the thermocouple’s junction terminals. This is
called the Junction Temperature.
Figure 24 - Thermocouple millivolt readings at various operating and junction temperatures
55
SECTION 3 - SERVICING COMPONENTS
D. Appendices
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • USA • (847) 741-3300 • FAX (847) 741-4406
Instructions for Service Kits P/Ns 33984 and 33985
Oven Thermocouple Kit
This Service Kit provides the parts and instructions necessary to replace one temperature-sensing or high limit thermocouple in any of the following Middleby Marshall oven models:
• PS200 Series uses Kit P/N 33985
• PS360 Series uses Kit P/N 33984
• PS536 uses Kit P/N 33985
• PS555 uses Kit P/N 33984
• PS570 uses Kit P/N 33984
These instructions include replacement procedures for ovens built with the current flanged thermocouple, AND for ovens
built with the obsolete thermocouple without a flange (P/N 28071-0001).
KIT CONTENTS - KIT P/N 33984
P/N
33812-1
B301A8861
21292-0001
27276-0001
41687
34701
Qty.
1
2
3
1
1
1
KIT CONTENTS - KIT P/N 33985
Description
Thermocouple, type J, 6” L
Screw, hex wshr hd #6 x 3/8”
Screw, hex wshr hd #10-16 x 3/4”
Cable clamp, nylon
Attachment plate, PS360 rear thermocouple
Instructions
P/N
33812-2
B301A8861
34701
Qty.
1
1
1
Description
Thermocouple, type J, 13-3/8” L
Screw, hex wshr hd #6 x 3/8”
Instructions
IMPORTANT - READ THIS BEFORE YOU BEGIN!
The thermocouple in your Kit has three leads:
• The red and white leads connect directly to the thermocouple terminals on the oven’s temperature controller (or high
limit control module, as appropriate), or to a local terminal block that in turn is connected to one of these units.
• The uninsulated lead is a ground wire for the thermocouple’s protective sheath. The ground connection helps to drain
any radio-frequency disturbances from the thermocouple before the signal enters the temperature controller or high
limit control module. For a temperature-sensing thermocouple, the ground lead MUST be connected to the ground
terminal on the temperature controller. For a high limit thermocouple, the ground lead should be connected to a
chassis ground or to the mounting screw for the high limit control module.
Some early thermocouples may have either two or four leads:
• The two-lead thermocouple is simply an earlier version of the current model, without the ground lead. When replacing
a two-lead thermocouple, it will be necessary to connect the new ground lead.
• The four-lead thermocouple is actually a dual-function unit which sends its signal to both the temperature controller
and the high limit control module. Current ovens use separate thermocouples for these functions. When replacing a
four-lead thermocouple, it will be necessary to use a SECOND KIT to install the high limit thermocouple. In addition,
any oven equipped with these early thermocouples should have all of its thermocouples updated at the same time. For
a PS570 or PS570S oven, this will require THREE THERMOCOUPLE KITS - two for the existing thermocouples, and
one for the new, separate high limit.
Oven Model
Page
PS200 Series - before 2/96, serial numbers before ASH-0001 ........... 2
PS200 Series - 2/96 or later, serial numbers after ASH-0001 ............. 2
PS360 Series rear wall thermocouples - before 2/96, serial
numbers before ASH-0001 ................................................................. 3
PS360 Series rear wall thermocouples - 2/96 or later, serial
numbers after ASH-0001 .................................................................... 3
PS360 Series front-mounted thermocouples inside the
machinery compartment ...................................................................... 4
PS536 ................................................................................................ 5
Oven Model
Page
PS555 Gas - rear wall thermocouples with screw terminal
connections (no terminal blocks) ......................................................... 8
PS555 Electric and PS555E ............................................................... 9
PS570 (X01-X05 name plate ID numbers) and PS570S
(early) with side-mounted thermocouples inside or outside
the blower motor compartments ........................................................ 10
PS570S (late) - rear wall thermocouples with left-side AND
right-side terminal block connections ................................................. 12
PS555G and PS570G - rear wall thermocouples with
left-side terminal block connections .................................................... 14
WARNING
BEFORE PERFORMING ANY SERVICE WORK, THE ELECTRICAL POWER SUPPLY AND THE GAS SUPPLY MUST BE TURNED OFF.
1
P/N 34701 • Rev. C • V1 • 11/01
56
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
PS200 Series - before 2/96, serial numbers
before ASH-0001
Figure 1
Thermocouple Installation - PS200 Series
Thermocouples on these ovens are located inside the machinery compartment. They are secured in place by a set
screw in the mounting tube, inside the plenum chamber.
Thermocouple
This Kit eliminates the set screw. The new thermocouple
is held in place by the head of the screw that is already
used to attach the mounting tube.
Mounting
tube
screw
Mounting
tube
Set screw
(not used with new
thermocouple)
Oven
wall
Tube
flange
Thermocouple
flange
NOTE FOR HIGH LIMIT THERMOCOUPLES:
CE ovens and PS200VL models have two thermocouples,
one mounted above the other. In these ovens, the upper
thermocouple senses the oven temperature and is connected to the temperature controller. The lower thermocouple is connected to the high limit control module. Either thermocouple can be replaced using this Kit.
1. Remove the lower end plug from the control end of the
oven. Then, remove 1 or 2 lower air fingers as necessary to access the thermocouple mounting tube.
2. Refer to Figure 1. REMOVE AND DISCARD the set
screw and pull the thermocouple out of the mounting
tube. Disconnect the thermocouple wiring from the temperature controller or high limit module, as appropriate.
CORRECT
Thermocouple flange sits firmly on
mounting tube flange; tube
mounting screw holds thermocouple in place.
3. Remove AND RETAIN the #10-16 screw that fastens
the flange of the thermocouple mounting tube to the
plenum wall. Leave the mounting tube in place.
Figure 2
Thermocouple Wiring - PS200 Series
4. Install the new thermocouple so that its flange fits firmly
against the mounting tube flange.
White
5. Replace the #10-16 screw that you removed in Step 3.
Check that the head of the screw holds the thermocouple flange securely in place, as shown in Figure 1.
Red
6. Route the thermocouple leads away from the ignition
cable. Connect the leads as shown in Figure 2.
Digital
Temperature
Controller
Shielded
ground lead
PS200 Series - 2/96 or later, serial numbers
after ASH-0001
White Red
Thermocouples on these ovens are located in the same
position as the earlier PS200 models described above.
However, these ovens feature a flanged thermocouple identical to the new thermocouple provided in this Kit.
Shielded
ground lead
Analog
Temperature
Controller
The thermocouple SHOULD be held in place by the screw
that attaches the thermocouple mounting tube, as per the
replacement procedure above. For these ovens, simply
disconnect the thermocouple wiring from the temperature
controller and follow Steps 3-6 of the procedure shown above
to remove and replace the thermocouple.
On some of these ovens, the thermocouple flange rests
ON TOP of the retaining screw for the mounting tube, as
shown in the “INCORRECT” inset of Figure 1. These thermocouples are held in place by the set screw on the mounting tube, inside the plenum chamber. For these ovens, you
should remove and replace the thermocouple by following
Steps 1-6 of the preceding section.
INCORRECT
Thermocouple flange sits on top of
screw head, leaving a gap as
shown.
Red
Shielded
ground lead
2
57
White
High Limit
Control
Module
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
PS360 Series rear wall thermocouples before 2/96, serial numbers before ASH-0001
Figure 3
Thermocouple Installation - PS360 Series
Thermocouples on these ovens are located on the rear wall
of the baking chamber. They are secured in place by a
clamp on the outside of the oven.
Mounting
tube
(welded to
plenum)
Thermocouple
This Kit eliminates the clamp. The flange of the new thermocouple is held to the back wall of the oven by a retaining
plate, as shown in Figure 3.
1. Loosen the retaining clamp and pull the thermocouple
straight out. Disconnect the thermocouple leads. Carefully thread the wiring out of the oven and discard the
thermocouple.
Clamp (remove
and discard if
present)
Thermocouple
flange
Plenum
wall
Oven
wall
2. Remove and discard the cable clamp.
New
thermocouple
3. Slide the new thermocouple into the mounting tube until
the flange is seated firmly on the back wall of the oven.
Retaining
plate
4. Install the kit-supplied retaining plate (P/N 41687) as
shown in Figure 3.
5. Fasten the attachment plate to the back wall of the
oven using the two kit-supplied #10-16 x 3/4” self-tapping screws. Ensure that the thermocouple flange is
securely trapped between the plate and the rear wall of
the oven.
#10-16 x 3/4”
mounting
screws (2)
6. Route the wiring through the grommet hole and into the
machinery compartment. Check that the leads are clear
of all components, PARTICULARLY THE BLOWER
MOTOR, by using the existing wiring bundles.
Figure 4
Thermocouple Wiring - PS360 Series
Digital Temperature Controller
7. Connect the leads as shown in Figure 4.
8. Attach the kit-supplied nylon clamp and #10-16 x 3/4”
screw to the rear of the oven. The clamp should be
positioned to support the thermocouple leads away from
the flue pipes and vent openings.
White
Red
PS360 Series rear-wall thermocouples - 2/96
or later, serial numbers after ASH-0001
Thermocouples on these ovens are mounted directly to the
back wall of the oven using a single retaining screw. It
should be possible to simply replace the existing thermocouple using the original mounting hardware.
Shielded
ground lead
To replace the thermocouple:
Analog Temperature Controller
1. Remove AND RETAIN the screw that holds the thermocouple in place on the rear wall.
White
2. Disconnect the thermocouple leads. Carefully thread
the wiring out of the oven and discard the thermocouple.
3. Slide the new thermocouple into the mounting tube until
the flange is seated firmly on the back wall of the oven.
4. Fasten the thermocouple to the back wall of the oven
using the original mounting screw. Then, perform Steps
6-8 of the preceding section to wire the thermocouple.
3
58
Red
Shielded
ground lead
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
PS360 Series front-mounted thermocouple
inside the machinery compartment
Figure 5
Thermocouple Installation - PS360 Series
Machinery Compartment
These thermocouples are mounted in a tube that extends
diagonally up and into the plenum chamber. They are secured in place by a set screw located on the mounting
tube, and by a bead of high-temperature silicone around
the end of the shaft.
Thermocouple
Set
screw
The new thermocouple will be held in place in the same
manner, except that the silicone should be applied so that
it wraps around the edges of the thermocouple’s mounting
flange.
NOTE FOR HIGH LIMIT THERMOCOUPLES:
PS310/360 electric ovens have two thermocouples inside
the machinery compartment. One thermocouple is connected to the temperature controller, while the other is
connected to the high limit control module.
High-temperature
silicone wraps around
thermocouple flange
and onto mounting
tube
Plenum
wall
Mounting
tube
The thermocouple supplied in this Kit is incompatible with
the early United Electric Type 54 and Type 55 high limit
control modules used on these ovens. If the oven is
equipped with one of these control modules, it will be
necessary to upgrade the control unit to the current
Watlow model (shown in Figure 6) before the thermocouple can be replaced. Service Kit 39733 includes all
parts and instructions needed for the conversion. Refer
to Service Bulletin MM-168 (5/7/99) for details.
Figure 6
Thermocouple Wiring - PS360 Series
White
Red
Digital
Temperature
Controller
1. Remove the silicone seal around the end of the thermocouple. Loosen the set screw.
2. Pull the thermocouple out of its mounting tube. Carefully thread the wiring out of the oven and discard the
thermocouple.
Shielded
ground lead
3. Check that the silicone has been removed completely
from the end of the mounting tube. Any remaining silicone can interfere with the correct placement of the
new thermocouple.
White Red
Shielded
ground lead
Analog
Temperature
Controller
4. Insert the new thermocouple until its flange is seated
on the end of the mounting tube. See Figure 5.
5. Tighten the set screw until the thermocouple is secure
inside the tube. AVOID OVERTIGHTENING THE SET
SCREW TO PREVENT DAMAGE TO THE THERMOCOUPLE.
Red
6. Use high-temperature silicone to seal the flange to the
mounting tube, as shown in Figure 5. Check that all
holes and spaces are filled by the silicone. This not
only helps to hold the thermocouple in place, but prevents heat from entering the machinery compartment.
Shielded
ground lead
7. Route the wiring for the new thermocouple through the
hole in the side of the electrical control box by using
the existing wiring bundle. Check that the leads are
clear of the ignition cable and all components.
8. Connect the leads as shown in Figure 6.
4
59
White
High Limit
Control
Module
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
PS536
Figure 7
Thermocouple Installation - PS536
Thermocouples on these ovens are located inside the machinery compartment. They are secured in place by a sheet
metal screw that traps the thermocouple flange against the
wall of the compartment. See Figure 7.
Sheet
metal
screw
NOTE FOR HIGH LIMIT THERMOCOUPLES:
PS536 ovens have two thermocouples, one mounted
above the other. The upper thermocouple senses the
oven temperature and is connected to the temperature
controller. The lower thermocouple is connected to the
high limit control module. Either thermocouple can be
replaced using this Kit.
Thermocouple
Thermocouple
flange
Machinery
compartment
wall
Plenum
wall
1. Loosen the sheet metal screw that holds the thermocouple flange to the wall of the machinery compartment.
Temperaturesensing
thermocouple
2. Pull the thermocouple out of the machinery compartment. Disconnect the thermocouple leads.
3. Install the new thermocouple so that its flange fits firmly
against the wall of the machinery compartment. Tighten
the sheet metal screw so that its head holds the thermocouple flange securely in place.
High limit
thermocouple
Screw head holds thermocouple
flange in place
NOTE: PS536 ovens do not use a thermocouple mounting tube, so it is CRITICAL that the thermocouple flange
is securely fastened to the wall of the machinery compartment.
Figure 8
Thermocouple Wiring - PS536
4. Route the thermocouple leads away from the ignition
cable. Connect the leads as shown in Figure 8.
Digital Temperature Controller
White
Red
Shielded
ground lead
High Limit Control Module
Red
Shielded
ground lead
5
60
White
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
PS555 Gas - thermocouples with screw terminal connections (no terminal blocks)
3. Disconnect the thermocouple leads. Refer to Figure 9.
Thermocouples on these ovens are located on the rear wall.
They are secured in place by two screws that are inserted
through the holes in the thermocouple flange. These ovens
are equipped with a three-lead, flanged thermocouple identical to the one in this Kit.
•
High limit thermocouples are wired directly to the
high limit control module. The thermocouple’s
ground wire is connected to the mounting screw
for the high limit control module.
•
The red and white leads from ALL temperature-sensing thermocouples are joined at capped screw terminals, located inside the left blower motor compartment. Leads from these screw terminals connect to the temperature controller at the front of the
oven.
NOTE FOR HIGH LIMIT THERMOCOUPLES:
These ovens have a high limit thermocouple installed in
the last mounting hole at the exit end of the oven.
The ground leads for temperature-sensing thermocouples are connected to the chassis ground lug
inside the left blower motor compartment.
The thermocouple supplied in this Kit can be used to
replace ANY of the temperature-sensing or high limit thermocouples on the oven.
4. Remove and discard the thermocouple.
1. Remove the rear shrouds and blower motor covers. This
allows access to the thermocouples (on the rear wall)
and screw terminals (inside the blower motor compartments).
5. Install the new thermocouple into the original mounting
hole. Fasten it in place with the supplied #6 x 3/8”
screws.
2. Remove the screws that hold the thermocouple to the
wall. Slide the thermocouple out of its mounting hole.
6. Wire the thermocouple as shown in Figure 9.
6. Use the kit-supplied nylon clamp and #10-16 x 3/4”
screw to secure the thermocouple leads so that they
will clear the shrouds, blower belts, and pulleys.
7. Close the machinery compartment door. Replace all
shrouds onto the oven.
Figure 9
Thermocouple Wiring - PS555
Temperature-sensing
thermocouple ground
leads attach to
ground lug
Cap
Screw terminals:
1 for red leads
1 for white leads
2 total
Red White
Temperature-sensing
thermocouple leads
(red or white)
+
1 lead to temperature
controller
Shielded
ground lead
High limit
thermocouple leads
attach directly to high
limit control module
6
61
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
PS555 Electric and PS555E
Note that all of the rear wall thermocouples are connected to the terminal block inside the left blower motor compartment. It is not necessary to access the
right blower motor compartment.
Temperature-sensing thermocouples on these ovens are located on the rear wall. High limit thermocouples are located inside the machinery compartment. All thermocouples are secured in place by two screws that are inserted through the holes in the thermocouple flange. These
ovens are equipped with a three-lead, flanged thermocouple
identical to the one in this Kit.
2. Remove the screws that hold the thermocouple to the
wall. Slide the thermocouple out of its mounting hole.
3. Disconnect the thermocouple leads. Rear wall thermocouples are connected to the terminal block inside
the left blower motor compartment. High limit thermocouples are connected directly to the high limit control
module.
NOTE FOR HIGH LIMIT THERMOCOUPLES:
PS555E electric ovens are equipped with a high limit thermocouple at the front of the oven, inside the machinery
compartment. All other PS555E, PS555G and PS570G
ovens have a high limit thermocouple installed into the
rear wall in the last mounting hole at the exit end of the
oven.
4. Remove and discard the thermocouple.
5. Install the new thermocouple into its mounting hole.
Fasten it in place with the supplied #6 x 3/8” screws.
The thermocouple supplied in this Kit can be used to
replace ANY of the temperature-sensing or high limit thermocouples on the oven.
6. Wire the thermocouple as shown in Figure 10.
7. If you replaced a rear wall thermocouple, use the kitsupplied nylon clamp and #10-16 x 3/4” screw to secure the thermocouple leads so that they will clear the
shrouds, blower belts, and pulleys.
1. If you will be replacing the high limit thermocouple, open
the machinery compartment door.
To replace any other thermocouple, first remove the
rear shrouds. Then, remove the cover over the left blower
motor. This allows access to the thermocouples on
the rear wall, and to the terminal block inside the blower
motor compartment.
8. Replace all shrouds onto the oven. Close the machinery compartment door.
Figure 10
Thermocouple Wiring - PS555 Electric and PS555E
Temperature-sensing
thermocouple leads
Red
White
Temperature-sensing
thermocouple leads
Ground
leads
Red
Shielded
ground lead
Left
Terminal
Block
High Limit
Control
Module
To temperature
controller
To ground
terminal on temp
controller
7
62
White
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
PS570 (X01-X05 name plate ID numbers) and
PS570S (early) with side-mounted thermocouples inside or outside the blower motor
compartments
7. Refer to Figure 11. Measure and scribe marks in the
rear wall of the oven for drilling the thermocouple mounting holes. Make sure that your measurements begin
at the edges of the rear panels, and NOT at the outer
edges of the oven!
These ovens are equipped with two thermocouples, one on
each end wall of the oven. The thermocouples may be
mounted either inside or outside of the blower motor compartments.
Note that there are two different thermocouple placement
locations: one for Pizza Hut (and Pizza Hut International,
or Tricon) ovens, and one for all other ovens.
•
The thermocouple on the right side of the oven has two
leads and sends its signal to the temperature controller.
8. Drill the new thermocouple mounting holes using an
11/32” (8.73mm) D x 8” (203mm) L bit. Make sure that
you drill through all three walls of the oven.
•
The thermocouple on the left side of the oven is a dualfunction unit. It has FOUR LEADS and sends individual signals to the temperature controller and the high
limit control module.
9. Drill the two screw mounting holes for each thermocouple using a 7/64” (2.78mm) bit. Tap the holes using
a #6-32 tap.
10. If necessary, remove air fingers from the oven to access the areas around the new thermocouple mounting holes.
Installing this Kit will replace BOTH thermocouples with
current three-lead versions located on the back wall of the
oven. The Kit also requires the installation of a THIRD thermocouple to act as a high limit sensor. Because of this,
you will need three separate thermocouple kits for these
ovens.
11. Vacuum out ALL drill shavings. If the oven is equipped
with a screen over the openings for the lower air fingers, use a flexible hose extension on the vacuum to
reach the shavings through the upper air finger openings.
If the oven has already been updated with the rear-wall thermocouple configuration, you can simply replace the affected
thermocouple. Follow the instructions for PS570S (late)
rear wall thermocouples on Page 10.
12. Reinstall the air fingers and end plugs onto the oven.
1. If the thermocouples are located outside the blower
motor compartments, remove and retain the thermocouple covers.
13. Install the three new thermocouples into the back wall
of the oven. Check that the thermocouple flanges are
flush with the back wall.
2. Remove the end plugs from the oven. Then, remove 1
or 2 air fingers from each end of the oven as necessary
to access the thermocouple mounting tubes.
14. Secure each thermocouple in place with the two kitsupplied #6 x 3/8” screws.
15. Wire the thermocouples as shown in Figure 12. The
thermocouples should be wired to the terminal block
inside the blower motor compartment closest to the
thermocouple.
3. Remove the rear shrouds. Open the blower motor compartment doors.
4. Remove the cooling fans from both blower motors. Then,
remove the blower belts.
IMPORTANT
As you wire the thermocouples, be sure to connect a
single chassis ground wire to the mounting screw for the
terminal block. See Figure 12.
5. For each thermocouple:
•
Disconnect the thermocouple leads from the terminal block inside the blower motor compartment.
•
Remove and discard the screws that hold the thermocouple mounting tube to the plenum wall. Remove and discard the thermocouple and tube.
•
Plug the internal and external openings left by the
tubes using a high-temperature silicone sealant.
A good ground connection for the thermocouple’s
uninsulated lead is REQUIRED for proper operation!
16. If you will be replacing additional thermocouples, repeat Steps 7-15 as necessary.
17. Using the kit-supplied nylon clamps and #10-16 x 3/4”
screws, secure the thermocouple leads to the back
wall of the oven so that they will clear the shrouds,
blower belts, and pulleys.
6. If the thermocouples were located outside the blower
motor compartments, replace the thermocouple covers.
18. Replace the blower belts and cooling fans.
19. Close the blower motor compartment doors. Replace
all shrouds onto the oven.
8
63
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
Figure 11
Location of New Thermocouple Mounting Holes - PS570, PS570S
High limit thermocouple
position for ovens with
LEFT-TO-RIGHT conveyors
High limit thermocouple
position for ovens with
RIGHT-TO-LEFT conveyors
Thermocouple positions
for non-Pizza Hut/Tricon ovens
Thermocouple positions
for Pizza Hut/Tricon ovens
Figure 12a
Thermocouple Wiring - PS570 and PS570S (early) after thermocouple update - Left to Right Conveyor
Left
Terminal
Block
Ground
lead
White
Red
(temp) (temp)
To temperature
controller
Red
White
Red
White
Ground
(temp) (temp) leads (all) (hi lim) (hi lim)
New chassis
ground wire
To temperature
controller
Right
Terminal
Block
To high limit
control module
Figure 12b
Thermocouple Wiring - PS570 and PS570S (early) after thermocouple update - Right to Left Conveyor
Left
Terminal
Block
White
Red
(hi lim) (hi lim)
Red
(temp)
Ground
White
Red
leads (all) (temp) (temp)
To high limit
control module
To temperature
controller
New chassis
ground wire
9
64
White Ground
(temp)
lead
To temperature
controller
Right
Terminal
Block
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
2. Remove the screws that hold the thermocouple to the
wall. Slide the thermocouple out of its mounting hole.
PS570S (late) - rear wall thermocouples with
left-side AND right-side terminal block connections
3. Disconnect the thermocouple leads. Remove and discard the thermocouple.
Thermocouples on these ovens are located on the rear wall
and are secured in place by two screws that are inserted
through the holes in the thermocouple flange.
4. Perform Step 4 ONLY if you are installing a high
limit thermocouple and no mounting hole is
present. This would be the case if the oven formerly used a four-lead thermocouple to send a
signal to the high limit control module.
Most of these ovens have either three or four thermocouples,
all installed in the back wall of the oven. The thermocouple
at the extreme exit end of the oven is the high limit thermocouple, while all other thermocouples send their signals to
the digital temperature controller. The thermocouple supplied in this Kit can be used to replace ANY of the thermocouples on these ovens.
Temperature-sensing thermocouples for these ovens should be installed in the two existing thermocouple mounting holes.
Some PS570S ovens are equipped with only two thermocouples. In these ovens:
• The thermocouple on the right side of the oven has two
leads and sends its signal to the temperature controller.
• The thermocouple on the left side of the oven is a dualfunction unit. It has FOUR LEADS and sends individual signals to the temperature controller and the high
limit control module.
• Installing this Kit will replace BOTH thermocouples with
current three-lead versions located on the back wall of
the oven. The Kit also requires the installation of a
THIRD thermocouple to act as a high limit sensor. Because of this, you will need three separate thermocouple kits for these ovens.
•
Refer to Figure 13. Measure and scribe marks in
the rear wall of the oven for drilling the high limit
thermocouple mounting hole. Make sure that your
measurements begin at the edges of the rear panels, and NOT and the outer edges of the oven!
•
Drill the new high limit thermocouple mounting hole
using an 11/32” (8.73mm) D x 8” (203mm) L bit.
Be sure to drill through all three walls of the oven.
Drill the two screw mounting holes for the high limit
thermocouple using a 7/64” (2.78mm) bit. Tap the
holes using a #6-32 tap.
•
1. Remove the rear shrouds and open the blower motor
compartment doors. This allows access to the thermocouples (on the rear wall) and terminal blocks (inside the blower motor compartments).
•
If necessary, remove the end plugs and air fingers
from the oven to access the areas around the new
high limit thermocouple mounting hole.
•
Vacuum out ALL drill shavings. If the oven is
equipped with a screen over the openings for the
lower air fingers, use a flexible hose extension on
the vacuum to reach the shavings through the upper air finger openings.
•
Reinstall the air fingers and end plugs onto the oven.
Figure 13
Location of High Limit Thermocouple Mounting Hole - PS570S
High limit thermocouple
position for ovens with
LEFT-TO-RIGHT conveyors
High limit thermocouple
position for ovens with
RIGHT-TO-LEFT conveyors
10
65
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
Figure 14a
Thermocouple Wiring - PS570S (Late) - Left to Right Conveyor
NOTE: This configuration
shows leads for three
temperature-sensing
thermocouples - two on the
left side, and one on the
right. Ovens with only two
temperature-sensing
thermocouples will have a
single set of leads on the
left terminal block, instead
of the two sets that are
shown.
Left
Terminal
Block
Ground
leads
To ground
terminal on temp
controller
White
Red
(temp) (temp)
Red
White
Red
White
Ground
(temp) (temp) leads (all) (hi lim) (hi lim)
To temperature
controller
To temperature
controller
To ground
To mounting screw
terminal on temp
for high limit
controller
control module
Right
Terminal
Block
To high limit
control module
Figure 14b
Thermocouple Wiring - PS570S (Late) - Right to Left Conveyor
NOTE: This configuration
shows leads for three
temperature-sensing
thermocouples - two on the
right side, and one on the
left. Ovens with only two
temperature-sensing
thermocouples will have a
single set of leads on the
right terminal block,
instead of the two sets
that are shown.
Left
Terminal
Block
To high limit
control module
White
Red
(hi lim) (hi lim)
Red
(temp)
Ground White
Red
leads (all) (temp) (temp)
To mounting screw
To ground
for high limit
terminal on temp
control module
controller
To temperature
controller
White Ground
(temp) leads
To temperature
controller
Right
Terminal
Block
To ground
terminal on temp
controller
5. Install the new thermocouple into its mounting hole.
Fasten it in place with the supplied #6 x 3/8” screws.
7. If you will be replacing additional thermocouples, repeat Steps 2-6 as necessary.
6. Wire the thermocouple as shown in Figure 14. The
thermocouples should be wired to the terminal block
inside the blower motor compartment closest to the
thermocouple.
8. Use the kit-supplied nylon clamp and #10-16 x 3/4”
screw to secure the thermocouple leads so that they
will clear the shrouds, blower belts, and pulleys.
9. Close the machinery compartment and blower motor
compartment doors. Replace all shrouds onto the oven.
IMPORTANT
As you wire the thermocouples, check that ground leads
run from the terminal blocks inside the blower motor compartments to BOTH the temperature controller AND the
high limit control module, as shown in Figure 14.
Figure 15
Alternate ground lead wiring
Use ONLY if ground leads to front compartment are not present.
White
Red
(hi lim) (hi lim)
If the ground leads to the front compartment of the oven
are NOT present - for example, on an oven that previously used the older-style 2-lead or 4-lead thermocouples
- it is acceptable to use a single chassis ground wire to
the mounting screw for the terminal block. See Figure
15.
Ground
White
Red
leads (all) (temp) (temp)
A good ground connection for the thermocouple’s
uninsulated lead is REQUIRED for proper operation!
New chassis
ground wire
11
66
To high limit
control module
To temperature
controller
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 33984 and 33985 Oven Thermocouple Kit, 11/01
PS555G and PS570G rear wall thermocouples
with left-side terminal block connections
2. Remove the screws that hold the thermocouple to the
wall. Slide the thermocouple out of its mounting hole.
Thermocouples on these ovens are located on the rear wall.
They are secured in place by two screws that are inserted
through the holes in the thermocouple flange. The ovens
are equipped with a three-lead, flanged thermocouple identical to the one in this Kit.
3. Disconnect the thermocouple leads from the terminal
block. Remove and discard the thermocouple.
4. Install the new thermocouple into its mounting hole.
Fasten it in place with the supplied #6 x 3/8” screws.
5. Wire the thermocouple as shown in Figure 16. Note
that the terminals are labeled - “TC” for temperaturesensing thermocouple leads, “G” for ground leads, and
“HL” for high limit thermocouple leads.
NOTE FOR HIGH LIMIT THERMOCOUPLES:
These ovens have a high limit thermocouple installed in
the last mounting hole at the exit end of the oven.
The thermocouple supplied in this Kit can be used to
replace ANY of the temperature-sensing or high limit thermocouples on the oven.
6. Use the kit-supplied nylon clamp and #10-16 x 3/4”
screw to secure the thermocouple leads so that they
will clear the shrouds, blower belts, and pulleys.
1. Remove the rear shrouds. Then, remove the cover over
the left blower motor. This allows access to the thermocouples on the rear wall, and to the terminal block
inside the blower motor compartment.
7. Replace all shrouds onto the oven.
Note that the thermocouples on these ovens are all
connected to the terminal block inside the left blower
motor compartment. It is not necessary to access the
right blower motor compartment.
Figure 16
Thermocouple Wiring - PS555G and PS570G
Red
(temp)
To temperature
controller
White
Ground
(temp) leads (all)
To ground
terminal on temp
controller
Red
(hi lim)
To mounting screw
for high limit
control module
White
(hi lim)
To high limit
control module
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • (847) 741-3300 • FAX (847) 741-4406
Middleby Corporation Service Hotline 1-800-238-8444
12
67
SECTION 3 - SERVICING COMPONENTS
Figure 25
Early-style PS200 indirect drive assembly
V. BLOWERS
A. PS200-series ovens
All PS200 ovens are equipped with one 1/3hp blower motor. The motor indirectly drives a pulley on the shaft of the
blower fan with a fan belt.
Two main designs exist for the PS200 indirect fan drive
assembly:
•
Early design, used through 6/90. This design used
1/2” (12.7mm) bore flange mount bearings and a 1/2”
(12.7mm) diameter blower fan shaft. See Figure 25.
•
Current design, used 7/90 and later. This design uses
5/8” (15.9mm) pillow block bearings and a 5/8” (15.9mm)
diameter blower fan shaft. See Figure 26.
Blower motors on both versions are rated for 208-240V,
single-phase, and are protected by:
•
A built-in thermal overload protection device.
•
Two 9A fuses on the inside of the machinery compartment door. Fuse location is shown in Figure 27.
Direction of rotation
(viewed from
rear of oven)
Figure 26
Current PS200 indirect drive assembly
In addition, the blower fan is protected by an air pressure
saftety switch that prevents the burner/heating elements
from activating if the fan is not rotating. See Air Pressure
Safety Switch on Page 81.
1. Part number reference
Early version components
NOTE: If an early-version PS200-series oven has a
failed fan shaft, upgrade the oven to the current drive
assembly using Kit P/N 49810-0121.
Part Number
Description
22230-0072
Pulley, 1/2” / 12.7mm bore
22071-0019
Bearing, 1/2” / 12.7mm bore, flange
mount
37900-0094
Fan shaft alignment tool (early)
27381-0066
Motor, 1/3 hp, 200-240V, 50/60Hz ,1 Ph
22181-0034
Fan belt
Direction of rotation
(viewed from
rear of oven)
Figure 27
Blower motor fuses
Current version components
Part Number
Description
35900-0232
Shaft, blower fan
22230-0073
Pulley, 5/8” / 15.9mm bore
22072-0025
Bearing, 5/8” / 15.9mm bore, pillow
block mount
27399-0003
Blower fan, 16” / 0.4m diameter
37900-0106
Fan shaft alignment tool (current)
49810-0121
Indirect drive upgrade kit (upgrades
early-style version to current version)
49810-0018
Fan shaft service kit (includes 2 bearings, 1 shaft, and alignment tool )
27381-0066
Motor, 1/3 hp, 200-240V, 50/60Hz ,1 Ph
22181-0034
Fan belt
Blower
motor
fuses
Control
fuse
68
SECTION 3 - SERVICING COMPONENTS
Figure 28
Bearing lubrication
2. Blower balancing and direction of rotation
Proper blower rotation is extremely important. From
the rear of the oven, the blower shaft pulley should turn
in a clockwise direction. See Figures 25 and 26.
Grease fittings
(1 per bearing,
2 total)
All blower fans are balanced at the factory. Any fan
found to be out of balance should be replaced. Vibration from an out-of-balance fan can cause poor baking
and premature bearing failure. Note that vibrations can
also be caused by other sources, including defective
motor or blower shaft bearings, loose bearings or motor mounting bolts, or an incorrectly tensioned fan belt.
3. Lubricating the blower fan shaft bearings
IMPORTANT: Middleby uses two different types
of grease in blower shaft bearings:
• DuPont Krytox® grease is used in some
PS536 ovens. Refer to Service Bulletin MM192 (included in the Appendices section of
this chapter) for details on identifying
Krytox® bearings.
Figure 29
Blower belt tension
• All other ovens use the standard Middleby
high-temperature grease, P/N 17110-0015.
1” (25mm)
vertical
deflection
Mixing grease types within the bearing will
cause the bearing to seize. For all PS200 ovens, be sure to use ONLY the standard
Middleby grease.
NOTE: Middleby recommends lubricating the blower
fan shaft bearings every three months.
Use a grease gun to lubricate the main blower fan shaft
bearings. See Figure 28. When lubricating the bearings:
•
•
Use a high-quality NLGI #2, lithium soap grease with
petroleum oil, such as Middleby P/N 17110-0015.
Add the grease slowly until a small bead of grease
is present at the seals. AVOID OVERGREASING.
Excessive greasing may cause harm to the bearing.
Figure 30
Repositioning the blower motor
Manually turn the blower shaft by pulling on the belt to
purge the grease. Wipe off any excess grease. The
oven cannot be operated until the rear shroud is replaced.
4. Blower belt tension
NOTE: Middleby recommends checking the blower
belt condition and tension every three months.
Check the blower belt for at least 1" (25mm) deflection
at the center, and for cracking or excessive wear.
Overtightening the belt will cause premature bearing
failure and possible vibrations. See Figure 29.
If necessary, adjust the tension of the belt by loosening
the two motor mounting bolts as shown in Figure 30.
Reposition the motor as neccessary until the correct
deflection is reached, then tighten the bolts.
69
Loosen bolts to
reposition motor
and adjust belt
tension
SECTION 3 - SERVICING COMPONENTS
5. Early-style PS200 bearing replacement and alignment
NOTE: This procedure is for early-style indirect fan
shaft assemblies only, as shown in Figure 25. Bearing
replacement procedures for the current-style indirect
fan shaft assembly (Figure 26) are provided on Page
72.
IMPORTANT: Before attempting any repair on the
early-style PS200 Indirect Fan Drive Assembly:
• If you need to perform any maintenance more
involved than replacing and aligning the shaft bearings, you should upgrade the fan shaft assembly
to the current version.
• Check the front and rear brackets (Item 6 in Figure 32). If the brackets ARE NOT welded together, you should upgrade the fan shaft assembly to the current version.
In either of these cases, you can upgrade the fan
shaft assembly using Service Kit P/N 49810-0121.
See Part Number Reference on Page 68 for details.
The following procedures are necessary to align the
fan shaft whenever service to the fan shaft or replacement of the bearings is required. REFER TO FIGURE
32 FOR ILLUSTRATIONS OF THE COMPONENTS DESCRIBED HERE.
NOTE: The bracket assembly is designed for slight up
and down and right to left movement to attain free shaft
rotation when the shaft alignment tool is in place. Once
free shaft rotation is achieved, tighten all eight bracket
screws (Item 2).
11. Tighten rear flange bearing block screws (Item 11)
then front flange bearing block screws.
12. Remove shaft alignment tool, then recheck fan shaft
for free rotation.
13. Install pulley (Item 8) on fan shaft and position fan
shaft per the dimensions shown in Figure 32. Align
the two flats per bearing which are machined on
fan shaft for the bearing set screws. Use High
Temperature Loctite, RC 620 on bearing set screws
and then tighten set screws. Recheck fan shaft for
free rotation.
14. Apply anti-seize compound on fan shaft before installing fan blade (Item 13). Position fan blade per
dimension shown in Figure 32.
15. Apply High Temperature Loctite Type RC 620 to
fan blade set screws.
NOTE: Tighten the two set screws on fan blade per
the following sequence when viewing fan blade from
front: first, the screw at the 12:00 position, then the
screw at the 3:00 position.
1. Remove the entire back wall (Item 1) of oven to
service the fan assembly.
16. Recheck fan shaft rotation before installing back
wall to oven cavity.
2. Remove the blower fan (Item 13) and pulley (Item
8).
NOTE: Apply anti-seize compound (MM P/N 171100017) to all 12 bolts before installing back wall assembly to oven.
NOTE: If parts are to be replaced, you should replace
them now.
3. When installing the Drive Bracket Assembly (Item
5) insert one 3/8” flat washer (Item 4) at the 4 outer
holes and one 3/8” special flat washer (Item 14) at
the 4 inner holes between bracket and back wall at
mounting locations. Use eight 3/8”-16 x 1” screws
(Item 2) and assemble a 3/8” lockwasher (Item 3)
and a 3/8” flat washer (Item 4) onto each screw.
Insert a screw at all 8 locations, hand tighten only
at this time.
4. Install front and rear fan shaft flange bearings (Item
10), if they were removed, to Indirect Drive Bracket
(Item 6) using three 1/4-20 x 3/4” screws (Item 11)
and three 1/4” lockwashers (Item12) on each bearing.
IMPORTANT: The bearings (10) must be mounted
so the grease fitting faces up when the bracket
assembly (Item 5) is mounted on the rear wall.
NOTE: Do not tighten flange bearing block screws
until Step 10 has been completed.
9. Install the fan shaft as shown in Figure 32. Align
bearing set screws with flats on shaft but do not
tighten set screws at this time.
10. Insert fan shaft alignment tool (Item 15) into back
wall as shown in Figure 31.
70
17. Install back wall on oven.
18. Install fan belt.
NOTE: Excessive fan belt tension will create overloading of rear bracket fan shaft bearing. Refer to Blower
Belt Tension on Page 69.
Figure 31
Fan shaft alignment tool
SECTION 3 - SERVICING COMPONENTS
Figure 32
Bearing replacement and alignment - early-style PS200 fan shaft assembly
Item Qty.
Part Number
Description
1
1
Not available
Back Wall Assembly
Item Qty.
9
1
Part Number
21651-0008
Description
Square Key 1/8”
2
8
21216-0001
Screw, Hex Cap SS 3/8-16x1”
10
2
22071-0010
Flange Bearing, 5/8” Bore
3
16
21422-0001
Lock Washer, Split 3/8”
11
6
21211-0004
Screw, Hex Cap 1/4-20 x 3/4”
4
20
21416-0001
Flat Washer, SS 3/8”
12
6
21421-0016
Lock Washer, Split 1/4”
5
1
Not available
Indirect Fan Drive Bracket Assembly
13
1
Not available
6
1
Not available
Bracket, Indirect Drive
14
4
21419-0004
Flat Washer 3/8” SS Special
7
1
Not available
Shaft, Fan Drive
15
1
37900-0094
Fan Shaft Alignment Tool
8
1
22230-0072
Pulley, 1/2” Bore
Blower Fan, 16” Dia.
IMPORTANT: If parts listed as “Not Available” require replacement, use Service Kit 49810-0121 to upgrade the fan shaft
assembly to the current version.
71
SECTION 3 - SERVICING COMPONENTS
6. Current-style PS200 bearing replacement and alignment
7. Insert fan shaft alignment tool (Item 13) as shown
into back wall.
NOTE: This procedure is for current-style indirect fan
shaft assemblies only, as shown in Figure 26. Bearing
replacement procedures for the early-style indirect fan
shaft assembly (Figure 25) are provided on Page 70.
NOTE: The bracket assembly is designed for slight up
and down and right to left movement to attain free shaft
rotation when the shaft alignment tool is in place. Once
free shaft rotation is achieved, tighten all eight bracket
screws (Item 2).
The following procedures are necessary to align the
fan shaft whenver service to the fan shaft or replacement of the bearings is required. REFER TO FIGURE
34 FOR ILLUSTRATIONS OF THE COMPONENTS DESCRIBED HERE.
8. Tighten rear pillow block bearing screws (Item 9)
then front pillow block bearing screws.
9. Remove shaft alignment tool, then recheck fan shaft
for free rotation.
1. Remove the entire back wall (Item 1) of oven to
service the fan assembly.
10. Install pulley (Item 7) on fan shaft and position fan
shaft per dimension shown in Figure 34. Align the
flats machined on fan shaft with the bearing set
screw holes. Apply High Temperature Loctite, type
RC 620 on bearing set screws and then tighten set
screws. Recheck fan shaft for free rotation.
2. Remove the blower fan (Item 11) and pulley (Item
7).
3. Remove the indirect drive bracket assembly (Item
5) by removing eight (8) screws (Item 2). lf you are
upgrading from the early-style assembly, save the
hardware (Items 2, 3, 4, and 12) to be reused with
the new style bracket (Item 5).
11. Apply anti-seize compound on fan shaft before installing fan blade (Item 11). Position fan blade flush
with 5/8” shoulder on shaft as called out in Figure
34.
NOTE: If parts are to be replaced, you should replace
them now.
4
NOTE: Fan blade hub has a 1/2” bore. The fan shaft
is turned down from 5/8” to 1/2” to receive fan blade.
Install front and rear fan shaft pillow block bearings
(Item 9), if they were removed, to indirect drive
bracket (Item 5) using two (2) 3/8-16 X 1” screws
(Item 2) and two 3/8” lockwashers (Item 10) on each
bearing.
12. Apply High Temperature Loctite Type RC 620 to
fan blade set screws.
NOTE: Tighten the two set screws on fan blade per
the following sequence when viewing fan blade from
front: first, the screw at the 12:00 position, then the
screw at the 3:00 position.
NOTE: Do not tighten the pillow block bearings
until Step 7 has been completed.
5. Install the fan shaft (Item 6) as illustrated in Figure
34. Align bearing set screws with flats on shaft but
do not tighten set screws at this time.
13. Recheck fan shaft rotation before installing back
wall to oven cavity. Be sure fan assembly has adequate clearance inside orifice ring and is not rubbing.
NOTE: Before proceeding to Step 6, it is advisable to
position the rear wall assembly in an upright, vertical
position using a block of wood under the fan ring.
NOTE: Apply anti-seize compound (MM P/N 171100017) to all 12 bolts before installing back wall assembly to oven.
6. When installing the drive bracket (Item 5) insert
one 3/8” flat washer (Item 4) at the four outer holes
and one 3/8” special flat washer (Item 12) at the 4
inner holes between the bracket and back wall at
the mounting locations. Use eight 3/8-16 X 1”
screws (Item 2) and assemble a 3/8” lockwasher
(Item 3) and a 3/8” flat washer (Item 4) into each
screw. Insert a screw at all 8 locations. Hand
tighten only at this time.
14. Install back wall on oven.
15. Check motor pulley and fan pulley alignment. See
Figure 33.
16. Install fan belt.
NOTE: Excessive fan belt tension will create overloading of rear bracket fan shaft bearing. Refer to Blower
Belt Tension on Page 69.
Figure 33 - Four-point alignment test for correct pulley alignment
Cord tied to shaft
Cord must touch sheaves at four points indicated by arrows
72
SECTION 3 - SERVICING COMPONENTS
Figure 34
Bearing replacement and alignment - current-style PS200 fan shaft assembly
Item Qty.
Part Number
Description
Item Qty.
Part Number
Description
1
1
37900-0068
Back Wall Assembly
11
1
27399-0003
Blower Fan, 16” Dia.
2
16
21216-0001
Screw, Hex Cap SS 3/8-16x1”
12
4
21419-0004
Flat Washer 3/8” SS Special
3
16
21422-0001
Lock Washer, Split 3/8”
13
1
37900-0106
Fan Shaft Alignment Tool
4
12
21416-0001
Flat Washer, SS 3/8”
5
1
37900-0101
Bracket, Indirect Drive
6
1
35900-0232
Shaft, Fan Drive
7
1
22230-0073
Pulley, 5/8” Bore
8
1
21651-0008
Square Key 3/16”
9
2
22072-0025
Pillow Block Bearing, 5/8” Bore
10
4
21422-0001
Lock Washer, Split 1/4”
Also available:
73
--
--
49810-0018
Fan Shaft Service Kit
Includes Qty. 2 of Item 9 and Qty. 1 ea.
of Items 6 and 13.
--
--
49810-0021
Fan Shaft Upgrade Kit
Includes parts and instructions to update early-style fan shaft assembly to
the current version shown here.
SECTION 3 - SERVICING COMPONENTS
Figure 35
Blower motor fuses - single-phase motors
B. PS360-series ovens
All PS360-series ovens are equipped with two blower motors.
• All gas ovens have motors rated at 230V, single-phase.
• All electric ovens built before 8/02 have three-phase
motors.
• All electric ovens built 8/02 or later that operate on a
supply voltage of 208-240V have single-phase motors.
• All electric ovens built 8/02 or later that operate on supply
voltages above 240V have three-phase motors.
Left motor
fuses - 9A
Right motor
fuses - 9A
Control
fuse - 5A
Blower motors are protected by:
• A built-in thermal overload protection device.
• For ovens with single-phase blower motors: Two 9A
fuses. Fuse location is shown in Figure 35.
• For ovens with three-phase blower motors: Three 5A
fuses. Fuse location is shown in Figure 36.
In addition, each motor contains a centrifugal safety switch
that prevents the burner/heating elements from activating if
either motor is not operating. See Blower Motor Centrifugal
Safety Switch on Page 80.
The blower wheel is directly connected to the motor shaft.
A heat slinger, also mounted on the motor shaft, helps to
keep heat away from the motor bearings. If the motor is
stopped when the temperature in the compartment is over
180°F/82°C, the bearings can be damaged.
Figure 36
Blower motor fuses - three-phase motors
Left motor
fuses - 5A
1. Part number reference
Control
fuse - 5A
Blower motors
Part Number
Description
27381-0023
1 Ph, 1/3 hp (PS310, -314, -360, -360S)
27381-0024
3 Ph, 1/3 hp (PS310, -314, -360)
27381-0054
1 Ph, 1/4 hp (PS360Q)
27381-0075
1 Ph, 1/2 hp (PS360WB)
31432
Right motor
fuses - 5A
1 Ph, 1 hp (PS360EWB, -WB70)
Blower wheels
Part Number
Part Number
(clockwise) (counter-clockwise) Description
22523-0002
22523-0003
9-3/16” / 233mm dia. (PS310, -314,
-360, -360Q, -360S, -360WB)
35603
35604
9-1/8” / 232mm dia. (PS360EWB)
36014
36015
8-1/4” / 210mm dia. (PS360EWBQ)
31599
31600
9-7/8” dia. / 251mm (PS360WB70)
Transformer fuses
(480V electric
ovens only)
Other components
Part Number
Description
27396-0005
Heat slinger
42400-0101
Blower wheel puller tool
2. Blower balancing
All blower wheels are balanced at the factory. Any
blower wheel found to be out of balance should be replaced. Vibration from an out-of-balance wheel can
cause poor baking and premature motor bearing failure. Note that vibrations can also be caused by other
sources, including defective motor bearings and loose
motor mounting bolts.
74
SECTION 3 - SERVICING COMPONENTS
3. Direction of blower rotation
4. Removing the blower wheels
Proper blower rotation is extremely important. Blower
rotation is determined by viewing the motor and wheel
from the REAR of the motor (or from the open end of
the oven). See Figures 37-39.
To change a motor or blower wheel, the wheel must
first be removed from inside the oven as follows:
Figure 37 - Clockwise blower wheel
Heat slinger
blades face motor
Direction
of rotation
•
Remove the end plugs and conveyor assembly.
•
From inside the oven cavity, reach into the blower
recess and remove the inlet rings. See Figure 40.
•
Loosen the set screw on the blower wheel hub and
remove the blower wheel. A special wheel puller
tool (P/N 42400-0101) is available for this purpose.
See Figure 41.
IMPORTANT: Before installing the new wheel,
apply an anti-seize lubricant (Middleby P/N 171100017) to the motor shaft and the inside of the blower
wheel hub.
Figure 40
Inlet ring
Note slant of blades
(rear view)
Figure 38 - Counterclockwise blower wheel
Direction
of rotation
Heat slinger
blades face motor
Note slant of blades
(rear view)
Figure 41
Blower wheel puller tool
Figure 39 - Blower wheel placement
Shown from rear of oven
Clockwise
Upper right
Counterclockwise
Lower right
Counterclockwise
Upper left
Clockwise
Lower left
75
SECTION 3 - SERVICING COMPONENTS
A. PS555/570-series ovens
All PS555/570-series ovens are equipped with two 1hp blower
motors. Each motor indirectly drives a pulley on the shaft
of a blower wheel with a fan belt.
The two designs share many common parts, including blower
wheels, motors, and bearings. From a service standpoint,
the major difference is the size of the pulleys and the length
of the belts.
Two main designs exist for the PS555/570 blower fan system:
• PS570/570S design. In this version, the pillow block
bearings for the blower wheel shaft were mounted upright, on brackets that were parallel to the fan belts.
See Figure 42.
• PS555/570G design. In this version, the pillow block
bearings are mounted with the grease fittings pointing
in towards the center of the oven. See Figure 43.
In addition, each blower fan is protected by an air pressure
saftety switch that prevents the burner/heating elements
from activating if the fan is not rotating. See Air Pressure
Safety Switch on Page 81.
Blower motors on all PS555/570-series ovens are rated for
208-240V, single-phase, and are protected by:
• A built-in thermal overload protection device.
• Two 15A fuses or 15A circuit breakers. Refer to Figure
44 for the location of the fuses/breakers.
Figure 42 - PS570/570S blower configuration
Blower
motor
Belt
Direction
of rotation
Pulley
Bearing
Blower
shaft
Pulley
Blower wheel
(inside oven)
Figure 43 - PS555/570G blower configuration
Blower
motor
Belt
Pulley
Bearing
Blower
shaft
Pulley
Blower wheel
(inside oven)
Figure 44 - Fuse/circuit breaker locations
PS570/570S:
15A fuses located on
left side of machinery
compartment
PS555 (early):
15A breakers located
inside left blower
motor compartment
76
PS555 (current),
PS570G: 15A
breakers located on
right side of machinery
compartment
SECTION 3 - SERVICING COMPONENTS
1. Part number reference
Part Number
Description
Part Number
Description
22072-0026
27381-0069
Motor, 1 hp, 208-240V, 50/60 Hz, 1 Ph
Bearing, pillow block, 1” / 25.4mm bore
(PS570)
22521-0005
Blower wheel, clockwise (right end of
PS570; left end of PS555, PS570S,
PS570G)
22072-0017
Bearing, pillow block, 1-7/16” / 36.5mm
bore (PS570S)
35210-0251
Blower shaft, 1” dia. (PS570)
35210-0506
Blower shaft, 1-7/16” dia. (PS570S)
22521-0006
Blower wheel, counterclockwise (left end
of PS570; right end of PS555, PS570S,
PS570G)
41899
Blower shaft, 1-7/16” dia. (PS555 or
PS570G)
Application
Oven
model
Hz
Blower Pulley
Part No. Desc.
Standard
PS570
60
22230-0084 BK52
30476
BK47
22181-0037
--
--
PS570S
60
22230-0087 BK47H
30476
BK47
46744
BX55
1780 RPM
PS570S
50
22230-0087 BK47H
22230-0086 BK55
46745
BX56
1733 RPM
PS570G
60
39587
BK70
44977
BK70
46452
BX67
1780 RPM
PS555/
555G/555E
60
39587
BK70
39586
BK80
44946
BX61
2080 RPM
PS570S
60
22230-0087 BK47H
22230-0086 BK55
46745
BX56
1733 RPM
PS570S
High Altitude
60
22230-0087 BK47H
PS570G
60
39587
PS570G
High Altitude
60
39587
PS570S
60
PS570G
60
39587
BK70
PS555G
50
39587
BK70
PS555E
50
39587
BK70
Domino’s “Q” PS570S
60
PS570G
60
39587
PS555G
60
39587
PS555G
60
39587
Pizza Hut
USA
Pizza Hut
Intl. (Tricon)
Papa John’s
Motor Pulley
Part No. Desc.
Belt
Part No. Desc.
Blower
RPM
39910
BK62
44963
BX58
2300 RPM
BK70
39586
BK80
46453
BX68
2057 RPM
BK70
46455
BK90
46454
BX70
2300 RPM
22230-0086 BK55
46745
BX56
1733 RPM
46453
BX68
2057 RPM
47044
BX62
2020 RPM
22230-0087 BK47H
39586
BK80
42984
BK95H
22031-0001 bushing
39586
BK80
44946
BX61
1680 RPM
45796
BK45
46744
BX55
1692 RPM
BK70
47267
BK65
46452
BX67
1692 RPM
BK70
39910
BK62
44963
BX58
1580 RPM
BK70
39910
BK62
44963
BX58
1580 RPM
22230-0087 BK47H
NOTE: If a particular customer/oven model combination is not listed (for example, Pizza Hut PS555G), use the
“Standard” information.
77
SECTION 3 - SERVICING COMPONENTS
Figure 45
PS500-series blower wheel orientation
2. Blower balancing and direction of rotation
Proper blower rotation is extremely important. Proper
blower rotation is shown in Figure 45.
Early PS570 blower wheels were positioned so that
the open end of the wheel faced into the baking chamber. This was changed on the PS570S (and all later
models) to improve airflow. Note that this also means
that on early PS570 ovens the counterclockwise wheel
is moved to the left side of the oven, and the clockwise
wheel moved to the right side, so that the wheel blades
point in the same direction. This is reflected in the
Part Number Reference information on Page 77.
All blower wheels are balanced at the factory. Any
blower wheel found to be out of balance should be replaced. Vibration from an out-of-balance wheel can
cause poor baking and premature bearing failure. Note
that vibrations can also be caused by other sources,
including defective motor or blower shaft bearings, loose
bearings or motor mounting bolts, or an incorrectly
tensioned fan belt.
Clockwise:
Right end
PS570:
Open end of wheel faces IN
Counterclockwise:
Left end
Counterclockwise:
Right end
PS570S, PS570G, PS555:
Open end of wheel faces OUT
Clockwise:
Left end
3. Lubricating the blower shaft bearings
IMPORTANT: Middleby uses two different types
of grease in blower shaft bearings:
• DuPont Krytox® grease is used in some
PS536 ovens. Refer to Service Bulletin MM192 (included in the Appendices section of
this chapter) for details on identifying
Krytox® bearings.
Note slant of blades
• All other ovens use the standard Middleby
high-temperature grease, P/N 17110-0015.
Mixing grease types within the bearing will
cause the bearing to seize. For all PS555/570series ovens, be sure to use ONLY the standard Middleby grease.
Figure 46
Bearing lubrication
Grease fittings
(1 per bearing,
4 total)
NOTE: Middleby recommends lubricating the blower
fan shaft bearings every three months.
Use a grease gun to lubricate the main blower fan shaft
bearings. See Figure 46. When lubricating the bearings:
•
•
PS570,
PS570S
Use a high-quality NLGI #2, lithium soap grease with
petroleum oil, such as Middleby P/N 17110-0015.
Add the grease slowly until a small bead of grease
is present at the seals. AVOID OVERGREASING.
Excessive greasing may cause harm to the bearing.
Grease fittings
(1 per bearing,
4 total)
Manually turn the blower shaft by pulling on the belt to
purge the grease. Wipe off any excess grease. The
oven cannot be operated until the rear shroud is replaced.
PS570G,
PS555
78
SECTION 3 - SERVICING COMPONENTS
Figure 47
Blower belt tension and
repositioning the blower motor
4. Blower belt tension
NOTE: Middleby recommends checking the blower
belt condition and tension every three months.
Check the blower belt for at least 1" / 25mm deflection
at the center, and for cracking or excessive wear.
Overtightening the belt will cause premature bearing
failure and possible vibrations. See Figure 47.
PS570,
PS570S
If necessary, adjust the tension of the belt by loosening
the two motor mounting bolts as shown in Figure 47.
Reposition the motor as neccessary until the correct
deflection is reached, then tighten the bolts.
1” (25mm)
vertical
deflection
5. Bearing replacement and alignment
Whenever service to the blower shaft or replacement of
the bearings is required, the shaft will need to be aligned.
NOTE: Apply anti-seize compound (MM P/N 171100017) to all bolts before installing back wall assembly
to oven.
PS570G,
PS555
First, reassemble the back wall components, but DO
NOT TIGHTEN THE HEX BOLTS that hold the bearings
to their mounting brackets. Leaving the bearings loose
allows the pulleys to be aligned.
Next, check the alignment of the pulleys using a cord
as shown in Figure 48. Reposition the bearings as
required to align the blower shaft, then tighten the hex
bolts to hold the shaft in place.
Replace the belts and rear shrouds after the pulleys
are properly aligned.
Loosen bolts to
reposition motor
and adjust belt
tension
Figure 48 - Four-point alignment test for correct pulley alignment
Cord tied to shaft
Cord must touch sheaves at four points indicated by arrows
79
SECTION 3 - SERVICING COMPONENTS
VI. BLOWER MOTOR CENTRIFUGAL SAFETY SWITCH
(PS360-SERIES)
VII. BURNER BLOWER MOTOR CENTRIFUGAL SAFETY
SWITCH (PS200-SERIES GAS, PS310, PS314,
PS360, PS360WB, PS570S)
Middleby ovens have a safety feature that prevents the
burner/heating elements from activating if the blower(s) are
not in operation. On PS360-series ovens, this feature is
controlled by a centrifugal switch mounted inside each
blower motor. If either motor is not operating, the burner/
heating elements cannot activate.
Middleby gas ovens with a 120V burner blower motor have
a centrifugal safety switch that prevents burner activation if
the burner blower motor is not in operation. This includes:
The centrifugal switch is a normally-closed (NC) limit switch
mounted inside the rear of each blower motor. See Figure
49. When the motor is not running, the centrifugal switch
weight holds the switch open. As the motor reaches full
speed, the weight moves away from the switch permitting
the contacts to close. When the switch contacts of BOTH
blower motors are closed, the heat circuit is completed,
allowingthe burner/heating elements to activate.
•
Most PS360-series ovens (except PS360WB70 and
PS360EWB);
•
PS200-series gas ovens (except units produced with
the modulating gas system);
•
All Model PS570S ovens.
Ovens with a 208/240V burner blower motor use a separate
air pressure safety switch to prove motor operation. See
Air Pressure Safety Switch on Page 81.
The centrifugal switch is a normally-closed (NC) limit switch
mounted inside each blower motor. When the motor is not
running, the centrifugal switch weight holds the switch open.
As the motor reaches full speed, the weight moves away
from the switch permitting the contacts to close. This completes the heat circuit, allowingthe burner to light.
If a blower motor is not operating, the switch will not close
and the circuit remains open, preventing burner/heating element activation.
A. Part Number Reference - Blower Centrifugal Switch
On all PS360-series blower motors, the centrifugal
switch can be replaced with switch P/N 27270-0144.
If the burner blower motor is not operating, the switch will
not close and the circuit remains open, preventing burner
activation.
B. Troubleshooting
1. To access the switch, remove the rear motor wiring
cover plates. See Figure 49.
No adjustment can be made to the switch. If it is not operating properly, the burner blower motor must be replaced.
2. When the switch is operating properly, both sides of
the brown wires coming from the switch should be “hot”
when the motor is at full RPM.
3. No adjustment can be made to the switch. If it is not
operating properly, it must be replaced.
Figure 49 - PS360-series blower motor centrifugal safety switch
Switch
80
SECTION 3 - SERVICING COMPONENTS
VIII. AIR PRESSURE SAFETY SWITCH (PS200-SERIES,
PS555/570-SERIES, PS360EWB, PS360WB70)
because of the presence of a centrifugal air switch inside
the motor housing (see Section VII, Burner Blower Motor
Centrifugal Safety Switch, on the previous page).
Middleby ovens have a safety feature that prevents the
burner/heating elements from activating if the blower(s) are
not in operation. On PS200-series ovens and PS555/570series ovens, this feature is controlled by a separate air
pressure switch that reads air flow from the blower. One
switch is used for each blower (1 for the PS200-series, 2
for the PS555/570 series).
The switch is an assembly that includes a normally-open
microswitch and a diaphragm. When the blower is at speed,
pressure is applied to the diaphragm which in turn closes
the microswitch. This completes the heat circuit, allowing
the burner/heating elements to activate.
If a blower is not operating, the microswitch receives no
signal from the diaphragm and cannot close, preventing
burner/heating element activation.
These ovens cannot use a centrifugal switch on the motor
because they use an indirect, belted drive system. If a belt
fails, it is possible for the motor to operate normally while
the blower itself is stopped.
A. Part Number Reference - Air Switches
Middleby has used four different types of air switches for
these applications. See Figure 50.
In addition, gas ovens with a line-voltage burner blower motor use an identical air switch to check that the burner blower
motor is operating before burner activation. These ovens
include the PS360EWB, PS360WB70, PS555, PS555G,
and PS570G, as well as PS200-series ovens equipped with
the modulating gas system. This additional air switch is
not necessary on ovens with a 120V burner blower motor
When replacing one of these switches, note that the “current” Yamatake-Honeywell air switch (#4 below) cannot be
used as an upgrade for an older switch. If you are replacing
Switches #1, #2 or #3 as shown in Figure 50, you should
use the Service Kits described for Switch #2.
Figure 50 - Air pressure safety switch models
1.
2.
Original-style round air switch
Replace with #2
Dungs square-case air switch with dial adjustment
Replace with same
Positive
pressure
Adjustment dial
(in. W.C. or
mbar)
Adjustment
screw
Positive
pressure
Negative
pressure
3.
4.
Dungs square-case “replacement” air switch with screw adjustment
Replace with #2
Yamatake-Honeywell air switch, non-adjustable
Replace with same
Adjustment
screw
Adjustment
screw
(fixed at proper
setting - cannot
be adjusted)
Positive
pressure
Negative
pressure
81
Positive
pressure
Negative
pressure
SECTION 3 - SERVICING COMPONENTS
1. Original-style round air switch with screw adjustment
(P/N 28023-0005)
•
•
This was the standard switch used through 9/96 and is
no longer available. If it must be replaced, use Kit P/N
35624 (for use in the USA) or 35625 (for export use).
See #2 below for a description of these kits.
Domestic switch: P/N 39530
CE-version switch: P/N 37498
If this switch must be replaced, use an identical switch.
Note that this is the ONLY time that you may use P/Ns
39530 and 37498 as service replacement parts.
B. Troubleshooting
2. Dungs square-case air switch with dial adjustment
1. Postive pressure vs. negative pressure
All air switches except the original round version can
sense either positive air pressure or negative air pressure. The connection that is actually made to the switch
depends on the application.
• If the switch is used to detect blower operation, the
tip of the pitot tube is located outside of the blower
wheel. This means that the pressure applied to
the end of the tube is positive. Because of this,
the tube should be connected to the positive side
of the switch.
• If the switch is used to detect burner blower operation, check the type of burner used on the oven.
- The Midco burner, used ONLY on some
PS360EWB and PS360WB70 ovens, has its
pitot tube mounted inside the blower wheel.
For correct operation, you should attach the
tube to the NEGATIVE side of the switch.
Refer to Figure 51 for an illustration of the Midco
burner.
- For ovens with the standard Wayne burner, the
pitot tube is mounted outside the blower wheel.
For correct operation, you should attach the
tube to the POSITIVE side of the switch.
Note that some PS360EWB and PS360WB70
ovens use the Wayne burner. You should always check the type of burner installed into
the oven before connecting the air tube. Refer
to Figure 52 for an illustration of a typical
PS360WB70/EWB gas train with the Wayne
burner.
This was the standard switch used from 9/96 through
1/02. It cannot be upgraded to the current YamatakeHoneywell octagonal switch, and so should still be used
as a service replacement. EXCEPTION: PS570G and
all PS555 ovens have used the Yamatake-Honeywell
switch throughout their production run (see #4 below).
Two different models were used; one for domestic ovens, and another for export ovens. The switches are
identical except for the markings on the dial. The domestic unit measures pressure in water column inches
(in. W.C.), while the export unit measures pressure in
millibars (mbar).
• Domestic switch: Kit P/N 35624
• Export switch: Kit P/N 35625.
3. Dungs square-case “alternate” air switch with threaded
screw-type adjustment (P/N 36194)
This switch was used on a limited number of domestic
production ovens in early 1997 to cover an availability
problem with the standard switch (see #2 above). Markings were in water column inches (in. W.C.). An export
version of this switch was never used.
This switch was never available as a service part. If it
must be replaced, use Kit P/N 35624 (see #2 above).
4. Yamatake-Honeywell air switch, non-adjustable
This switch is the current standard for all new-production Middleby ovens. You may NOT use this switch as
an upgrade on an oven equipped with an older switch.
Two different models are used; one for dometic and
standard export ovens, and another for CE-approved
ovens.
Figure 51
PS360WB70/EWB with Midco burner
Figure 52
PS360WB70/EWB with Wayne burner
Connects to
negative pressure
side of air switch
Connects
to positive
pressure
side of air
switch
82
SECTION 3 - SERVICING COMPONENTS
C. Appendices
Appendix - Instructions for Service Kits 35624 and 35625 Air Pressure Switch Replacement Kits, 1/97
83
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kits 35624 and 35625 Air Pressure Switch Replacement Kits, 1/97
84
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions to Replace an “Alternate” Air Switch
P/N 36194 with Service Kit P/N 35624, 3/97
85
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions to Replace an “Alternate” Air Switch
P/N 36194 with Service Kit P/N 35624, 3/97
86
SECTION 3 - SERVICING COMPONENTS
B. Flame Gate Orientation
IX. PS570/570S FLAME GATE
To check the position of the flame gate, view it through
the oven’s window. See Figure 53. The gate must
point towards the EXIT end of the oven. Note that this
directs the flame from the burner tube towards the ENTRANCE end of the oven, as described above.
All PS570/570S ovens produced for Pizza Hut USA through
8/00 were equipped with an adjustable flame gate at the
end of the burner tube. The purpose of the flame gate was
to direct heat towards the entrance end of the oven to better suit the customer’s cooking needs.
All ovens were originally shipped from Middleby Marshall
with the gate pointing to the right. This is because all
ovens were shipped with left-to-right conveyors. If the
conveyor direction of one of these ovens is reversed in
the field, the flame gate should be repostioned as follows:
PS570S ovens produced 9/00 or later, as well as all PS570G
ovens, are not equipped with the flame gate. The introduction of the modulating gas system to these ovens, as well
as improvements to the customer’s air finger configuration
and baking specs, make the flame gate unneccessary on
these ovens.
A. Part Number Reference - Flame Gate
Part No.
Description
35210-0555
Flame gate
35210-0511
Adjustment rod
35210-0510
Clamp
•
Loosen (do not remove) the two 7/16” hex bolts on
the clamps that hold the adjustment rod in place.
•
Insert a #2 Phillips-head screwdriver into the hole
in the rod as shown in Figure 53. Swing the handle
of the screwdriver to rotate the rod and move the
flame gate. You should position the gate as far as
possible towards the EXIT end of the conveyor as
shown.
•
Remove the screwdriver. Tighten the two screws
to hold the clamps in place.
Figure 53
PS570/570S flame gate adjustment
RIGHT-TO-LEFT conveyor travel
(factory setting)
LEFT-TO-RIGHT conveyor travel
(factory setting)
Direction of
conveyor travel
Direction of
conveyor travel
Gate points to
RIGHT (exit)
end of oven
Gate points to
LEFT (exit)
end of oven
Metal clamps
hold rod in
place
7/16” hex
bolts (2)
Rotate screwdriver
handle to reposition
flame gate
87
SECTION 3 - SERVICING COMPONENTS
X. GAS TRAIN AND BURNER SYSTEM
A. Part Number Reference Gas Train Components
Figure 54
PS200-series gas train
Air shutter
42810-0087
Burner blower and motor assy
OVENS WITH ON/OFF
GAS SYSTEM ONLY:
120V motor assy with centrifugal
safety switch 27170-0011
OVENS WITH MODULATING
GAS SYSTEM ONLY:
208/240V motor assy 27170-0287
OVENS WITH
MODULATING GAS
SYSTEM ONLY:
M420 modulating
valve, 1/2”
41647
OVENS WITH ON/OFF
GAS SYSTEM ONLY:
Junction box
Includes:
240Vp:120Vs
transformer 27170-0017
Combination gas
control valve, 1/2”
45688
Relay 27170-0016
1/2” union
23051-0003
Bypass line
(1/4” aluminum
tubing)
15125-0002
(per foot)
Manual shutoff
valve, 1/2”
23115-0009
Pilot line
(1/4” aluminum
tubing)
15125-0002
(per foot)
Pilot
pressure
tap
30185
OVENS WITH
ON/OFF GAS
SYSTEM ONLY:
Solenoid valve, 1/2”
28091-0017
Figure 55
PS310, PS314, PS360 or PS360WB gas train
Burner blower and motor assy, 120V
with centrifugal safety switch
27170-0011
Air shutter
42810-0087
Solenoid valve, 1/2”
28091-0017
Combination gas
control valve, 1/2”
45688
Junction box
Includes:
240Vp:120Vs
transformer
27170-0017
1/2” union
23051-0003
Relay
27170-0016
Manual shutoff
valve, 1/2”
23115-0009
Bypass line
(1/4” aluminum tubing)
15125-0002
(per foot)
88
Pilot
pressure
tap
30185
Pilot line
(1/4” aluminum
tubing)
15125-0002
(per foot)
SECTION 3 - SERVICING COMPONENTS
Figure 56
PS360EWB or PS360WB70 gas train with Midco burner
PS360WB70
ONLY:
Bypass line
(1/4” aluminum
tubing)
15125-0002
(per foot)
PS360WB70 ONLY:
Solenoid valve, 3/4”
31500
PS360EWB ONLY:
M420 modulating
valve, 3/4”
32570
Air tube
(silicone rubber)
22450-0297
(per foot)
TO NEGATIVE (-)
SIDE OF AIR
SWITCH
Air shutter
36830
Burner blower
motor,
208/240V
32195
3/4” union
23051-0004
Manual shutoff
valve, 3/4”
23115-0010
Pilot
pressure
tap
Combination gas
control valve, 3/4”
32569
Pilot line
(1/4” aluminum tubing)
15125-0002
(per foot)
Main orifice
See chart on
Page 69
Pilot orifice
See chart on
Page 69
Figure 57
PS360EWB or PS360WB70 gas train with Wayne burner
PS360WB70 ONLY:
Solenoid valve, 3/4”
31500
PS360EWB ONLY:
M520 modulating
valve, 3/4”
32570
Combination gas
control valve, 3/4”
32569
PS360WB70 ONLY:
Bypass line
(1/4” aluminum tubing)
15125-0002
(per foot)
Air tube
(silicone rubber)
22450-0297
(per foot)
TO POSITIVE (+)
SIDE OF AIR
SWITCH
Air shutter
42810-0087
Burner blower
and motor assy,
208/240V
27170-0287
3/4” union
23051-0004
Manual shutoff
valve, 3/4”
23115-0010
89
Pilot line
(1/4” aluminum
tubing)
15125-0002
(per foot)
Pilot
pressure
tap
30185
SECTION 3 - SERVICING COMPONENTS
Figure 58
PS570S gas train
OVENS RETROFITTED
WITH MODULATING
GAS SYSTEM ONLY:
M420 modulating
valve, 1/2”
41647
Burner blower and
motor assy, 120V
with centrifugal
safety switch
27170-0011
Flexible air hose
22450-0255
1/2” union
23051-0003
Air shutter
42810-0087
Pilot line
(1/4” aluminum tubing)
15125-0002
(per foot)
Manual shutoff
valve, 1/2”
23115-0009
Combination gas
control valve, 1/2”
45688
Solenoid valve, 1/2”
28091-0017
Bypass line
(1/4” aluminum tubing)
15125-0002
(per foot)
Pilot
pressure
tap
30185
NOT SHOWN
(components are
installed on back wall
of machinery
compartment):
240Vp:120Vs blower
motor transformer
27170-0017
Relay
27170-0016
Figure 59
PS570G or PS555 gas train
Air shutter
42810-0087
Combination gas
control valve, 1/2”
45688
M420 modulating
valve, 1/2”
41647
Pilot line
(1/4” aluminum tubing)
15125-0002
(per foot)
Burner blower
and motor assy,
208/240V
27170-0287
1/2” union
23051-0003
Manual shutoff
valve, 1/2”
23115-0009
Flexible air hose
22450-0255
Pilot pressure tap
30185
90
Air tube
(silicone rubber)
22450-0297
(per foot)
TO POSITIVE (+)
SIDE OF AIR
SWITCH
SECTION 3 - SERVICING COMPONENTS
Figure 60 - Wayne burner - exploded view
Pilot/ignitor
assembly
42810-0117
Venturi
Pilot shield
27170-0204
Wtih angled flame target:
27170-0223
Burner blower and motor assy
With round flame target:
38127
208/240V: 27170-0287
120V: 27170-0011
Air shutter
42810-0087
Main orifice
See chart below
Pilot orifice
See chart below
Pitot tube assembly
(for use with 208/
240V motors)
42400-0640
B. Part Number Reference - Gas Orifices and Gas Conversion Kits
PS200
PS220/224
PS310/314/360
PS360WB
42810-0125
42810-0126
42810-0120
42810-0127
22176-0010
22176-0016
22176-0004
0.204”/5.18mm
0.182”/4.62mm
0.219”/5.56mm
22174-0011
22174-0011
22174-0011
0.028”/0.71mm
0.028”/0.71mm
0.028”/0.71mm
22174-0006* 22174-0006*
PS360WB70/EWB PS360WB70/EWB
Midco burner
Wayne burner
PS555
PS570S/PS570G
Description
43061
42810-0127
GAS CONVERSION KIT,
PROPANE TO NATURAL
MAIN ORIFICE, NATURAL
GAS
36863
44664
22176-0014
31821
22176-0014
43059
22176-0014
0.250”/6.35mm
0.234”/5.94mm
0.250”/6.35mm
0.228”/5.79mm
0.250”/6.35mm
22174-0011
31818
22174-0011
22174-0011
22174-0011
0.028”/0.71mm
0.032”/0.81mm
0.028”/0.71mm
0.028”/0.71mm
0.028”/0.71mm
22174-0006
22174-0006
0.060”/1.52mm/
#53 drill
0.060”/1.52mm/
#53 drill
0.060”/1.52mm/
#53 drill
0.060”/1.52mm/
#53 drill
0.060”/1.52mm/
#53 drill
0.060”/1.52mm/
#53 drill
28092-0019
28092-0019
28092-0019
28092-0019
28092-0019
28092-0019
28092-0019
28092-0019
GAS VALVE SPRING KIT,
NATURAL GAS
42810-0122
42810-0123
42810-0119
42810-0124
36856
44665
43062
42810-0124
GAS CONVERSION KIT,
NATURAL TO PROPANE
22176-0007
22176-0017
22176-0003
22176-0015
31822
31980
43060
22176-0015
MAIN ORIFICE, PROPANE
0.1285”/3.26mm
0.113”/2.87mm
0.134”/3.40mm
0.152”/3.86mm
0.185”/4.70mm
0.165”/4.19mm
0.141”/3.58mm
0.152”/3.86mm
22174-0010
22174-0010
22174-0010
22174-0010
31819
22174-0010
22174-0010
22174-0010
0.018”/0.45mm
0.018”/0.45mm
0.018”/0.45mm
0.018”/0.45mm
0.025”/0.64mm
0.018”/0.45mm
0.018”/0.45mm
0.018”/0.45mm
22174-0009* 22174-0009*
22174-0006* 22174-0006*
22174-0009
22174-0009
0.038”/0.97mm/
#62 drill
0.038”/0.97mm/
#62 drill
0.038”/0.97mm/
#62 drill
0.038”/0.97mm/
#62 drill
0.038”/0.97mm/
#62 drill
0.038”/0.97mm/
#62 drill
28092-0018
28092-0018
28092-0018
28092-0018
28092-0019
(same as
natural gas)
28092-0018
*
NONE*
PILOT ORIFICE, NATURAL GAS
22174-0006* BYPASS ORIFICE, NATU0.060”/1.52mm/
RAL GAS
#53 drill
22174-0009* 22174-0009*
NONE*
PILOT ORIFICE, PROPANE
22174-0009* BYPASS ORIFICE, PRO0.038”/0.97mm/
PANE
#62 drill
28092-0018
28092-0018
GAS VALVE SPRING KIT,
PROPANE
NOTE
Bypass orifices are used ONLY on ovens equipped with an on-off gas regulation system (with a solenoid valve). These ovens include:
•
PS200-series
(through 3/02)
•
•
PS310
PS314
•
•
PS360
PS360WB
•
•
PS360WB70
PS570S (through 8/00)
Ovens equipped with a PID modulated gas system (with a modulating valve) do not use a bypass orifice. These ovens include:
•
PS360EWB
•
PS570S
•
PS200-series
•
PS570G
•
PS555
(9/00 or later)
(4/02 or later)
NOTE: Installations at higher altitudes have a lower ambient air pressure that disrupts the air-fuel mixture. To correct this
problem, smaller gas orifices are required. A general rule is a 4% reduction for each 1000 ft. (305m) above sea level. Refer
to the chart in the Appendices section (page 135) for a listing of orifice sizes showing this reduction.
91
SECTION 3 - SERVICING COMPONENTS
1. Solenoid valve vs. Modulating valve
C. Component Identification
Middleby ovens use one of the following systems for
gas flow regulation:
1. Burner type
Middleby ovens are equipped with one of two main burner
designs. Details of these burners are provided below.
•
1. Midco burner - see Figure 61. This burner was
used on PS360WB70 and PS360EWB ovens only.
Late-production PS360EWB and PS360WB70 ovens used the Wayne burner shown in Figure 62. In
addition, many PS360EWB ovens were retrofitted
during 1998 to use the Wayne burner.
Servicing the Midco burner is beyond the scope of
this manual. However, note that most gas train
components EXCEPT FOR THE BURNER ITSELF
are identical to the components used with the
Wayne burner. If necessary, contact Middleby Technical Service for assistance.
On-Off gas flow regulation is used on the following
Middleby oven models:
-
PS200-series
- PS360WB
(through 3/02)
- PS360WB70
- PS310
- PS570S
- PS314
(through 8/00)
- PS360
Additional information on the solenoid valve is provided in Solenoid Valve on Page 96.
2. Wayne burner - see Figure 62. Wayne burners are
used on all Middleby oven models except earlyproduction PS360WB70 and PS360EWB models.
The Wayne burner configuration varies slightly between oven models and so may be slightly different from that shown in Figure 62. Refer to the
drawings in Part Number Reference - Burner Components (pages 88-90) for illustrations of the burner
configuration used on each oven model. Common
variants include:
•
Flexible air tube between the burner blower and
plenum. Used on all PS555/570 series ovens.
•
120V burner blower motor. Used on PS200series (through 3/02), PS310, PS314, PS360,
PS360WB and PS570S ovens.
•
208/240V line voltage blower motor. Used on
PS200-series (4/02 or later), PS360WB70,
PS360EWB, PS555, and PS570G ovens.
On-Off gas flow regulation. These ovens are
equipped with a high flame solenoid valve. The
solenoid valve can only be positioned fully open
(100% gas flow) or fully closed (0% gas flow) as
necessary to maintain the set point. A bypass line
supplies gas to maintain the flame when the valve
is closed. On/off gas systems have a temperature
“swing” of several degrees on either side of the set
point.
•
Modulated gas regulation. These ovens are
equipped with a modulating gas valve. The modulating valve can open or close at any setting from 0100% gas flow in response to the need for heat to
maintain the set point. Because of this flexibility,
the temperature “swing” is eliminated.
The modulated gas system is used on the following
Middleby oven models:
- PS200-series
- PS570S
(4/02 or later)
(9/00 or later)
- PS360EWB
- PS570G
- PS555
Additional information on the modulating valve is
provided in Modulating Valve on Page 97.
Figure 61 - Midco burner
Figure 62 - Wayne burner
PS360EWB shown. For different oven models, refer
to the drawings on pages 88-90.
Burner blower
Air
shutter
Plenum
Burner
blower
Main gas
line
Burner
blower
motor
Main gas
line
Plenum
Pilot line
Pilot line
92
Burner
blower
motor
Air shutter
SECTION 3 - SERVICING COMPONENTS
Figure 63 - Pilot/ignitor assembly
D. Pilot/Ignitor Assembly
The pilot assembly is attached to the end of the pilot line.
It consists of an ignitor electrode/flame sensor, a pilot shield
and the pilot burner. See Figure 63.
Pilot line
connects here
Pilot
burner
The pilot assembly includes a safety circuit. An electrical
current is sent to the flame sensor probe to prove the presence of the pilot flame. When the spark ignites the pilot, a
circuit is completed THROUGH THE FLAME from the flame
sensor probe to the pilot burner, which is grounded. This
safety circuit must be completed before the pilot will light.
Hood
1. Pilot Shield
The pilot shield is a plate located on the bottom of the
pilot. It prevents drafts, etc. from blowing the pilot flame
away from the sensing probe. See Figure 64.
Ignitor/sensor
probe
Spark cable
connects here
2. Flame target
The flame target aids in distributing the flame from the
end of the venturi. See Figure 65.
•
PS310/360-series ovens built prior to 6/87 are not
equipped with a flame target. The burner on these
ovens resembles the one shownin Figure 64.
•
The angled flame target is used on:
- PS200-series ovens built through 3/02.
- PS310, PS314, PS360 and PS360WB ovens
built 6/87 or later.
- PS570S ovens.
All of these ovens use a 120V burner blower motor.
Most units equipped with the 120V burner blower
motor also use the angled flame target.
•
The round flame target is used on:
- PS200-series ovens built 4/02 or later.
- PS360EWB and PS360WB70 ovens equipped
with the Wayne burner system.
- PS555 and PS570G ovens.
All of these ovens use a 208/240V burner blower
motor. All ovens equipped with the line voltage
burner blower motor use the round flame target.
Figure 64
End of burner without flame target
showing pilot shield
Pilot
shield
Figure 65
Flame targets
Angled
target
Round
target
93
SECTION 3 - SERVICING COMPONENTS
3. Pilot and Proof of Pilot Flame
Rectification
With standing pilots, heat is
a necessary ingredient for
proper thermocouple operation. But this is not the case
with IIDS (Intermittent Ignition
Device Systems) when flame
conduction or rectification is
used. To better understand the
principles of flame conduction
and rectification, we must first
understand the structure of a
gas flame. See Figure 66.
Figure 66
Flame structure
Figure 67 - Flame rectification
Figure 68 - Pilot and probe
With the proper air-gas ratio to give a blue pilot flame,
three zones exist.
Zone 1: An inner, fuel-rich cone that will not burn because excess fuel is present.
Zone 2: Around the inner, fuel-rich cone is a blue envelope. In this area is a mixture of vapor from the fuel-rich
inner cone and the secondary, or surrounding, air. This
is where combustion occurs.
Zone 3: Outside the blue envelope is a third zone that
contains an excessive quantity of air and will not burn.
Of concern is the second, or combustion area. This is
where the burning occurs and is the area that is of
prime importance for good flame sensor location.
Flame Rectification
With flame rectification, two probes with different surface areas are exposed to a flame - in this case, the
pilot flame. The probe with the larger surface area attracts more free electrons and, as a result, becomes
the negative probe. Therefore, current is conducted
through the flame from the positive probe to the negative probe. See Figure 67.
THE FOLLOWING CONDITIONS WILL HAVE A DIRECT
BEARING ON EVERY IID APPLICATION:
Voltage
Note also that the AC voltage sine wave has not
changed, but the negative portion of the current sine
wave has been chopped off. This positive portion now
represents a DC current. This is the phenomenon of
flame rectification.
The supply voltage to the ignition controls should be
within the following ranges:
• 120VAC controls – 102 to 132VAC
• 24VAC controls – 21 to 26.5VAC
24VAC systems should use transformers that will provide adequate power under maximum load conditions.
To apply this principle to an IID (Intermittent Ignition
Device - in this case, the pilot/ignitor assembly), a pilot
and flame sensor have been substituted for the two
probes (See Figure 68). After the pilot is ignited, a DC
current flow of 2.0mA (microamps) or more is conducted
through the flame, from the flame sensor (the positive
probe) to the pilot tip (the negative probe). The pilot tip,
acting as the negative probe, completes the circuit to
ground. The IID sensing circuit uses this DC current
flow to energize a relay and open the main burner gas
valve.
Gas Pressure
Inlet gas pressures
•
•
•
Natural gas, Wayne burner - 6-12” W.C. (14.9-29.9 mbar)
Propane, Wayne burner - 11½-12” W.C. (28.7-29.9 mbar)
Midco burner (all gases) - 6-14” W.C. (14.9-34.9 mbar)
Regulated gas pressures
•
•
Natural gas, Wayne burner - 3.5” W.C. (8.7 mbar)
Propane, Wayne burner - 10” W.C. (24.9 mbar)
•
Midco burner (all gases) - 3-5” W.C. (7.5-12.5 mbar)
Pilot gas pressures
94
•
•
•
Natural gas, Wayne burner - 3½-4” W.C. (8.71-9.95 mbar)
Propane, Wayne burner - 8-10” W.C. (19.9-24.9 mbar)
Midco burner (all gases) - 5-6” W.C. (12.5-14.9 mbar)
SECTION 3 - SERVICING COMPONENTS
Temperature
Ignition controls should not be exposed to temperatures exceeding 140°F (60°C) or less than -40°F (-40°C).
Pilot Application
The pilot and flame sensor application is the most critical aspect of the llD application.
The pilot flame must make contact with the pilot tip
and surround the flame sensor probe. A multimeter or
ampmeter set to read microamps (mA) is necessary to
verify that the proper amount of current is being maintained through the pilot flame. The minimum value
required is 2.0 mA. Rectification-based ignition systems respond in less than 0.8 of a second to a loss of
flame. If the minimum signal is not being maintained
at all times, OR if the pilot flame is briefly directed
away from the flame sensor or pilot tip, the main gas
valve may cycle rapidly (“chattering”) or the burner may
be prevented from activating.
Other conditions that can cause the failure of the main
burner to activate, OR chattering of the burner, are:
1. Pilot flame is too small.
2. Gas pressure is too low for proper pilot flame impingement on the flame sensor.
In these cases, the pilot may ignite, but the main burner
gas valve will not be energized. It is also possible for
drafts or unusual air currents to deflect the pilot flame
away from the flame sensor. Deflection of the pilot
flame may also be caused by main burner ignition concussion or roll-out of the main burner flame.
An additional point to be considered is the condition of
the pilot flame. If the pilot flame is hard and blowing,
the grounding area of the pilot is reduced to a point
where the necessary current is not being maintained,
and a shutdown of the system will result.
The positioning of the flame sensor is also critical in
the pilot application. Positioning of the flame sensor
should be such that it will be in contact with the second, or combustion area of the pilot flame. Passing
the flame sensor through the inner cone of the pilot
flame is not a recommended procedure. For this reason, a short flame sensor may provide a superior signal over a longer one. The final determination of the
sensor location (length) is best determined by the use
of a multimeter set to read microamps (mA).
E. Burner Blower Motor
The burner blower motor is located on the side or top of the
burner housing. Some blowers use a flexible tube to connect the blower to the burner, depending on the available
space inside the machinery compartment. The burner
blower motor drives a blower wheel located in a housing
attached to the end of the motor that is the primary air
supply for combustion. The motor requires no lubrication.
Depending on the oven model, the burner motor operates
on either 120V or 208/240V (line voltage). 120V motors
have an internal centrifugal switch that controls the 24V
power supply to the gas valve (see Burner Blower Motor
Centrifugal Safety Switch on Page 80). 208/240V motors
use a separate air pressure safety switch to sense blower
operation (see Air Pressure Safety Switch on Page 81).
This safety feature prevents burner operation in case of motor
failure.
Figure 69
Air shutter adjustment
Wayne burner
Standard openings:
• 1/4”/6.4mm for natural gas ovens
• 3/8”/9.5mm for propane ovens
Clockwise less air
Loosen hex
nut to adjust
shutter
Counterclockwise more air
F. Air Shutter
The air shutter is a round metal plate located on the open
end of the burner blower wheel. Adjusting the position of
the shutter will increase or decrease the amount of air that
is permitted into the plenum for combustion. Rotate the
plate in a counterclockwise direction to increase the air
supply, or in a clockwise direction to reduce the air supply.
You can insert a drill bit into the shutter gap to check the
size of the opening. Refer to Figure 69 for the recommended
opening sizes.
Early Midco burners use an adjustment screw on the front
wall of the plenum to adjust the airflow. If it is not possible
to adjust the air supply properly using the screw, a retrofit
kit is available (P/N 36829) to install the external air shutter
shown in Figure 69.
95
Midco burner
Standard opening 5/16”/7.9mm (all gases)
Clockwise less air
Loosen
screw to
adjust
shutter
Counterclockwise more air
SECTION 3 - SERVICING COMPONENTS
G. Burner Transformer
pass line that goes around the solenoid valve. This allows
the burner to operate in low flame mode while awaiting reactivation.
120V burner blower motors feature a transformer located in
the electrical junction box on the burner. In PS570S ovens,
AND all ovens with 208/240V burner blower motors, the
transformer is located inside the machinery compartment.
When the oven has been fully preheated and has maintained the set point for about an hour with a moderate product load, the low flame to high flame ratio should be approximately 1 to 1. That is, the oven will be calling for heat
approximately half the time. To check this ratio, refer to
the HEAT indicator on the temperature controller, which will
only be active when the burner is on high flame.
The transformer supplies 24V to the burner motor relay (if
present) and also to the 24V gas valve through the motor’s
centrifugal switch (or air pressure safety switch).
H. Burner Motor Relay
120V burner blower motors feature a 24V time delay relay
located in the electrical junction box on the burner. In
PS570S ovens, the relay is located on the back wall of the
machinery compartment.
EXCEPTION: Older PS310/314/360 ovens have a temperature-sensing thermocouple mounted at the front of the oven,
inside the machinery compartment. On these ovens, the
low flame to high flame ratio should be approximately 2 or 3
to 1 (oven calls for heat 1/3 or 1/4 of the time).
Approximately 25 seconds after power is applied to the coil
of the relay, the contacts will close and complete a circuit
to the burner blower, allowing the motor to operate. This
15-30 second delay is a prepurge for a cold start. When
the coil of the relay is warm, the delay is bypassed.
IMPORTANT: For proper functioning of the solenoid valve, the temperature controller MUST be
set to the on-off operating mode. Refer to Temperature Controller on Page 31.
Ovens with 208/240V burner blower motors are not equipped
with the burner motor relay, and do not have a prepurge for
a cold start.
J. Bypass (Low Flame) Orifice (ovens with a high
flame solenoid valve only)
I. High Flame Solenoid Valve (if so equipped)
All ovens that use an on-off gas regulation system are
equipped with an orifice in the low flame bypass line. See
Figure 70.
Ovens that use an on-off gas regulation system are equipped
with a high flame solenoid valve. The valve is located between the combination gas control valve and the burner.
The valve operates on 110-120V.
When the oven is not calling for heat, the solenoid valve is
closed, but gas is still supplied to the burner through the
bypass line. This allows the burner to operate in low flame
mode while awaiting re-activation.
The valve opens when the oven’s temperature falls 2 degrees Fahrenheit below the set point, and closes when the
temperature rises to 2 degrees above the set point. Because of residual heat within the oven, however, the temperature swing after preheating is about 5 degrees Fahrenheit above and below the set point.
The low flame orifice regulates the gas flow through the
bypass line. If the orifice size is too large, the low flame
will be too high. In some cases, this will prevent the oven
from being able to maintain the set point.
The solenoid valve can only be positioned fully open (100%
gas flow) or fully closed (0% gas flow). While the valve is
closed, gas is still supplied to the burner through the by-
Refer to the chart on Page 91 to determine the proper size
for the bypass orifice.
Figure 70
Low Flame (Bypass) Orifice
Bypass line configuration varies depending on the oven model. Refer to the drawings on pages 88-90.
Low flame
(bypass)
orifice
Solenoid
valve
Bypass
line
96
SECTION 3 - SERVICING COMPONENTS
The modulating valve features a bypass adjustment screw,
shown in Figure 71. For all ovens except the PS536, the
screw should ALWAYS remain fully closed; no adjustment
is necessary. The screw is pre-set to the fully-closed position from the factory. If the screw is adjusted to any setting
other than fully-closed, the oven may not be able to maintain the set point temperature.
K. Modulating Gas Valve (if so equipped)
Ovens that use a PID (modulated) gas regulation system
are equipped with a modulating gas valve instead of a solenoid valve. The valve is located between the combination
gas control valve and the burner.
In response to the millivolt signal from the thermocouple,
the Digital Temperature Controller sends a 4-20mA signal
to an amplifer board. The board, in turn, passes on a 020VDC signal to the modulating valve itself. The valve opens
or closes proportionally to the signal from the amplifier board,
allowing any setting from 0-100% gas flow.
IMPORTANT: For proper functioning of the modulating valve, the temperature controller MUST be
set to the PID operating mode. Refer to Temperature Controller on Page 31.
When the oven is switched on, gas demand is at its peak
and the valve is fully open, permitting 100% gas flow. As
the oven’s temperature approaches the set point, the valve
slowly begins to close, restricting gas flow to the 35-60%
range. After the oven is fully preheated, the gas flow usually stabilizes at about 30%. The actual oven temperature
can remain constant, with NO temperature swing, because
the valve is adjusted constantly according to the demand.
L. Amplifier Board (ovens with a modulating gas
valve only)
Ovens equipped with a modulating gas valve have an amplifier board mounted inside the machinery compartment.
Modulating valves are used on all PS360EWB, PS555, and
PS570G gas ovens. They are also used on PS200 ovens
produced 4/02 or later and PS570S ovens produced 9/00 or
later.
In response to the millivolt signal from the thermocouple,
the Digital Temperature Controller sends a 4-20mA signal
to the amplifer board. The board, in turn, passes on a 020VDC signal to the modulating valve. The valve opens or
closes proportionally to the signal from the amplifier board,
allowing any setting from 0-100% gas flow.
The Model PS360EWB oven uses a Maxitrol M520 modulating valve with a 3/4” gas line, P/N 32570. All other
Middleby oven models equipped with a modulating valve
use the Maxitrol M420 valve with a 1/2” gas line, P/N 41647.
All Middleby oven models equipped with a modulating valve
use amplifier board P/N 31651.
Figure 71 - Modulating Gas System
Digital Temperature
Controller
To transformer
24VAC input
orange/white
MUST BE SET TO PID
OPERATING MODE
orange
white +
To thermocouple
blue
red -
blue/white
purple/white
Modulating Valve
bypass adjustment
screw (under cap)
MUST BE FULLY
CLOSED
purple
Amplifier Board
To amplifier board terminal 6
To amplifier board terminal 5
97
purple
purple/white
PS360EWB
with Controller 32571
only
SECTION 3 - SERVICING COMPONENTS
3. Servicing the Combination Valve
• Pilot pressure
M. Combination Gas Control Valve
1. Part Number Reference - Combination Gas Valve
•
PS360WB70 and PS360EWB ovens are equipped with
a 3/4” (19.05mm) gas line. This requires the use of
Combination Gas Valve P/N 32569. The valve has a
tan plastic cover with a blue On/Off knob.
•
All other oven models are equipped with a 1/2” (12.7mm)
gas line.
- Through 10/01 - these ovens used Valve P/N 280920017. The valve operated on a 60 Hz supply, had a
tan plastic cover and a blue On/Off knob.
- 11/01 and later - these ovens use Valve P/N 45688.
The valve operates on a 50 or 60 Hz supply, has a
grey plastic cover and a black On/Off knob. It is
otherwise identical to the previous version, and may
be used to replace it in all cases.
One of the more common service issues with the combination valve occurs on ovens with the on/off gas regulating system (with a solenoid valve), when the oven is
on low flame. During low flame, the servo can “bounce”
inside the valve as it searches for the proper level. The
bouncing line pressure can also cause surges in the
pilot pressure. A properly adjusted pilot will tend to
smooth out the surges.
The best way to check for a properly adjusted pilot is
to check the pilot line pressure. This requires a pilot
pressure tap in the pilot line. Ovens built 3/94 or later
should have the tap installed in the line. The tap is
also available as Service Kit P/N 30185 which includes
installation instructions.
Recommended pilot gas pressures are:
- Wayne burner, natural gas - 3½-4” W.C. (8.71-9.95
mbar)
- Wayne burner, propane - 8-10” W.C. (19.9-24.9
mbar)
- Midco burner (all gases) - 5-6” W.C. (12.5-14.9
mbar)
2. Valve Operation
When the ON-OFF knob on the valve is in the ON position,
gas is allowed to enter the valve. Once 24VAC is supplied
to the valve, gas is supplied to the pilot line.
When the pilot flame has been proved (see Pilot and Proof
of Flame Rectification on Page 94), 24VAC is supplied to
the combination valve by the ignition module, opening the
main valve. Gas pressure from the inlet side of the valve is
passed through the Pressure Regulator. The regulated pressure is supplied to a cavity below the main valve diaphragm.
This pressure overcomes the spring force and moves the
main valve to its open position. During operation, the main
valve is opened and closed by the pressure regulator to
keep a constant pressure at the outlet of the valve.
•
Burrs in pilot adjustment portal
Some combination valves have been shown to have
shipped with small burrs in the pilot adjustment portal.
Although this will not interfere with proper operation of
the valve in any way, it does make it difficult to adjust
the pilot pressure until the burr is removed.
Check for a burr by attaching a manometer to the pilot
pressure tap. If the manometer does not detect any
change in pilot pressure when the screw is tightened
all the way down, there is probably a burr in the portal.
When power to the valve is cut, the cavity below the main
valve diaphragm is depressurized and the valve spring closes
the main valve rapidly to shut off the main burner.
To remove a burr, perform the following procedure:
- Turn the adjustment screw all the way down.
- Apply more pressure to break through the burr.
- Back the screw out until the top of the screw is
level with the top of the access hole.
- Turn the adjustment screw back down to adjust
the pressure.
- Repeat these steps until the burr is cleared.
When the 24VAC supply to the valve is cut, the valve stops
gas flow to both the pilot and the main burner.
The combination valve includes taps to measure both the
inlet pressure and the regulated pressure. To ensure accuracy, the regulated pressure should be measured when the
oven is on low flame.
Figure 72 - Combination Gas Control Valve
Pressure
regulator
adjustment
(under cap
screw)
Regulated
pressure
tap
Inlet
pressure
tap
On/Off knob (should
remain in ON position)
Pilot line
connection
98
Pilot pressure
adjustment (under
cap screw)
SECTION 3 - SERVICING COMPONENTS
N. Ignition Module
If you are replacing the obsolete module (P/N 271610004) with the current version (P/N 27161-0005), BE
SURE TO DISCONNECT THE MODULE FROM THE
COMMON GROUND WITH THE TRANSFORMER AND
RELAY. Double-grounding of the module creates a feedback voltage circuit that allows the module to operate
without a signal from the burner/blower assembly. This
procedure is explained in greater detail in the instructions for Kit 42810-0114, included in the Appendices
section.
1. Part Number Reference - Ignition Module
•
PS360WB70 and PS360EWB ovens equipped with the
Midco burner use Ignition Module P/N 31501.
•
For all other oven models:
-
Through 10/90 - these ovens used Ignition Module
P/N 27161-0004. Some versions of this module
included a separate, replaceable fuse. This module shared a common ground with the 24V transformer and the relay coil. See Figure 73.
-
11/90 or later - these ovens use Ignition Module
P/N 27161-0005, included in Service Kit 428100114. The module is internally grounded and the
common ground with the transformer and relay coil
has been eliminated. See Figure 74.
2. Module Operation
The ignition module delivers 24V to the pilot ignitor when
the blower motor centrifugal switch (or air pressure safety
switch) is closed.
When the module detects a current flow of at least 2.0 mA
through the pilot flame, it supplies 24V to the combination
gas control valve, allowing the valve to operate.
Figure 73
Wiring diagram of ignition and gas valve system (obsolete ignition module 27161-0004)
Figure 74
Wiring diagram of ignition and gas valve system (current ignition module 27161-0005)
99
SECTION 3 - SERVICING COMPONENTS
O. Gas Conversion Kits
P. Burner and Gas Train Troubleshooting
Ovens can be converted from natural gas to propane operation, or from propane to natural gas operation, by the installation of the appropriate Gas Conversion Kit. Refer to Part
Number Reference - Gas Orifices and Gas Conversion Kits
on Page 91 for a listing of kit part numbers.
1. Burner Blower Motor
Converting the oven to operate on a different gas type generally requires:
•
If there is 110V (or 208/240V, as appropriate) to the
motor terminals, it should be running. If the motor is
not running, replace it.
2. Burner Blower Motor Centrifugal Switch (or air pressure
safety switch)
If the burner blower motor is running at top speed, and
you cannot measure 24V across the supply terminals
of the ignition module, the centrifugal switch is not closing properly and is either loose or defective.
Replacement of the regulator spring on the combination gas control valve. The spring is located underneath the pressure regulator screw. Note that on
PS360EWB and PS360WB70 ovens equipped with the
Midco burner, replacement of the regulator spring is
not necessary.
•
Replacement of the main orifice, pilot orifice, and bypass orifice.Note that ovens equipped with the modulating gas system do not use a bypass orifice.
•
Adjustment of the main and pilot gas pressures.
•
Documenting the gas conversion using the labels and
tags supplied in the kit.
Instructions for the gas conversion kits are provided in the
Appendices section.
For 120V burner blower motors with an internal centrifugal switch, tighten the switch. If this fails to correct
the problem, replace the motor.
For 208/240V burner blower motors with a separate air
pressure safety switch, refer to Air Pressure Safety
Switch on Page 82 to troubleshoot the switch.
3. Relay
•
•
Connect a voltmeter across the supply terminals on
the relay. The reading should be 24V. If you do not get
a 24V reading, the transformer should be replaced.
lf 24V is present at the relay, and if after 15 to 45 seconds you do not get 110V (or 208/240V, as appropriate) on terminal 3 of the relay, replace the relay.
4. Main Gas Valve and Ignition Module
If 24V can be measured across the ignition module
supply terminals, there should also be 24V between
terminals PV and MV/PV on the gas control module.
If you have a 24V reading, the pilot valve should be
open and the spark should be on to ignite the pilot gas.
When the pilot gas has ignited, the main burner should
ignite. If not, check MV terminal to ground and see if
24V is present. If no voltage is present, replace the
ignition module.
It is possible to have a pilot on, but have the spark
continue to try to light the pilot. If this continues for
more than 30 seconds, then it should be assumed that
the flame sensor is not working properly. This can be
easily checked. Refer to Control Module Flame Sensor
Test on the next page.
A reading of 2.0 mA or greater should be obtained. If a
poor reading is obtained, the pilot flame and sensor are
probably not making good contact. This will keep the
main valve from opening. Refer to the section on flame
rectification. If the microamp reading is good and 24V
cannot be obtained at terminal MV then the ignition
module should be replaced.
100
SECTION 3 - SERVICING COMPONENTS
5. Burner Operation
b. Restart the system and read the meter. The flame
sensor current must be at least 2.0 mA, and the
reading must be steady. If the reading is below 2.0
mA or if the reading is unsteady, check the pilot
flame and electrical connections as described
above. Also, replace the ignitor/sensor if the ceramic insulator is cracked.
a. Shut off the manual gas valve for oven. Turn the
Burner and Heat switches ON. The spark should
begin at the pilot burner within 30 seconds.
With the manual gas valve turned off, no gas will be
present; so, the spark will continue for the lockout
timing period of 90 seconds.
If the reading still is unsteady, it may be necessary
to adjust the pilot pressure. Refer to Pilot Pressure under Servicing the Combination Valve on Page
98.
b. Turn the Heat switch OFF, then turn on the gas
supply. Set the temperature controller set point
above the actual oven temperature.
c. Turn the Heat switch ON. The system should start
as follows:
•
Spark turns on and pilot gas valve opens at
once. Pilot burner ignites after gas reaches
the pilot burner.
•
Spark cuts off when pilot flame is established.
•
Main gas valve opens and main burner lights
after gas reaches the burner ports.
8. System Troubleshooting.
Start the system by setting the temperature controller
above room temperature, and observe the system response.
Establish the type of system malfunction or deviation
from normal operation by using the Intermittent Pilot
System Troubleshooting Table on Page 103.
Use the table by following the questions in the boxes.
If the condition is true (answers yes), go down to the
next box. If the condition is not true (answers no), go
to the box alongside.
NOTE: Main burner flame may not be satisfactory until
the gas input and combustion air have been adjusted.
6. Check Grounding
Continue checking and answering conditions in each
box until a problem and/or the repair is explained. Use
the Component Checks section as necessary to perform system checks.
Electrical ground connections must be clean and tight.
If the lead wire is damaged or deteriorated, use only
No. 14 to 18 gauge, moisture-resistant thermoplastic
insulated wire with a 221°F (105°C) minimum rating as
a replacement.
After any maintenance or repair, the troubleshooting
sequence should be repeated until the procedure ends
with normal system operation.
Excessive temperature at the ceramic flame rod insulator can also permit electrical leakage to ground.
Examine the flame rod and mounting bracket, and correct if it is bent out of position. Replace the ignitor/
sensor if the insulator is cracked.
Figure 75
Voltage Checks for Ignition Module and
Combination Gas Valve
7. Ignition Module Flame Sensor Circuit Test
The ignition module provides AC power to the ignitor/
sensor which the pilot burner flame rectifies to direct
current (DC). If the flame signal back to the control
module is not at least 2.0 mA DC, the system will lock
out.
Ignition Module
Voltage
The output of the flame sensing circuit cannot be
checked directly, so check the flame sensing circuit
indirectly by checking the flame sensing current form
the ignitor/sensor to the control module as follows.
a. Connect a ampmeter or multimeter set to read DC
microamps (mA) in series with the flame signal
ground wire. Disconnect the ground wire at the
control module. Connect the red (positive) lead of
the meter to the free end of the ground wire. Connect the black (negative) meter lead to the ground
terminal on the ignition module.
Test Points Marked
Fused
Nonfused
MV/PV to PV
3 VAC
24 VAC
MV/PV to MV
12 VAC
24 VAC
Combination Gas Valve
TR to TH
12 VAC
24 VAC
TH/TR to TR
3 VAC
24 VAC
NOTE: Information on the fused ignition module is provided
for reference only. All ovens produced 1988 or later use the
nonfused module. The fused module is no longer available.
101
SECTION 3 - SERVICING COMPONENTS
9. Component Checks Reset System After Lockout
c. Check the connections to the ignitor and ignition
module terminals. All connections must be clean
and tight. Loose connections may not conduct a
flame current even though the ignition spark is satisfactory. Check the electrical continuity of the
cable. Replace the cable if it is damaged or deteriorated.
If the oven enters safety lockout, the system must be
reset before attempting further operation or checkout.
The system will remain in safety lockout until it is reset. Shut system OFF. (Turn Heat switch OFF.) Wait
at least five minutes, then turn Heat switch ON.
10. Check Spark Ignition Circuit
d. If no spark or a weak spark occurs, but the spark
ignition circuit checked normally, disconnect the
ignition cable at the ignitor/sensor and measure
the arc from the cable end to the ignitor stud. Follow the same general procedures and observe the
same cautions as in Step 10, Check Spark Ignition Circuit, above.
The electronic module and step-up transformer in the
ignition module provide spark ignition at 15,000V (open
circuit). This circuit can be checked at the ignition
module as follows:
a. Turn OFF the gas flow at the manual shutoff valve.
b. Disconnect the ignition cable at the ignition module terminal to isolate the circuit from the pilot
burner/ignitor sensor, and prepare a short jumper
lead using heavily insulated wire, such as a spare
ignition cable.
c. Energize the ignition module and touch one end of
the jumper firmly to the control board ground terminal (GND). Do not disconnect the existing ground
lead. Move the free end slowly toward the stud
terminal to establish a spark and then pull the lead
wire slowly away from the stud. Note the length of
the gap at which arcing stops.
d. An arc length of 1/8” (3.2mm) or more indicates
satisfactory voltage output. Replace the ignition
module if no arc can be established or if the maximum gap is less than 1/8” (3.2mm), and power to
the ignition module input terminals was correct.
If the arc is correct, replace the ignitor/sensor.
If the arc is less than it should be, disconnect the ignition cable and use a jumper wire from the ignition module stud terminal. If the spark is normal, replace the
ignition cable. If the arc is still smaller than normal,
replace the ignition module.
Q. Checking the Gas Pressures
All gas pressures should be checked using a manometer
at the supplied pressure taps, as follows:
•
Inlet pressure can be checked at the inlet pressure tap
on the combination gas valve. See Figure 72 (on Page
98).
•
Regulated pressure can be checked at the outlet pressure tap on the combination gas valve. See Figure 72
(on Page 98).
WARNING
Do Not touch either stripped end of jumper or stud
terminal. This is a very high voltage circuit and
electrical shock can result. Perform the test immediately upon energizing the system, before the
ignition module enters safety lockout and interrupts the spark circuit.
11. Check Spark Ignitor
Current PS555/570-series ovens provide an additional
regulated pressure tap in the main gas line, just before
the line enters the burner. This allows you to connect
a SECOND manometer downstream of the modulating
valve to check that the valve is functioning properly.
We encourage you to use this tap to diagnose problems with the modulating valve whenever possible.
•
If the troubleshooting procedure indicates a problem
with the ignitor/sensor, check the spark ignitor and the
ignition cable connections and continuity as follows:
Check Ignitor/Sensor
a. Check the ignitor spark gap to make certain it is
correct, 1/8” (3.2mm). If necessary, use a
needlenose pliers and carefully bend the tip of the
outer electrode to the correct gap.
b. Check that the pilot flame is properly adjusted.
Check Igniton Cable
a. The ignition cable must not touch metal surfaces
or current-carrying wires. Use ceramic standoff
insulators, if necessary.
b. Check the length of the ignition cable. It must not
exceed 3 ft. (0.9 m).
102
Pilot gas pressure can be checked at the pilot pressure tap. For ovens with a Wayne burner, the tap is
located on the pilot line. For PS360EWB/WB70 ovens
with a Midco burner, the tap is located on the end of
the pilot orifice fitting. Refer to the illustrations on Pages
88-90.
Some older ovens (pre-1994) with Wayne burners may
not be equipped with a pilot pressure tap. If you encounter problems with an erratic pilot (see Servicing
the Combination Valve on Page 98), it may be necessary to install a tap. Middleby offers Service Kit P/N
30185 which includes the pilot pressure tap and instructions. A copy of the instructions are also provided
in the Appendices section.
IMPORTANT: Any older oven that has a pilot pressure
tap installed should have the combination gas valve replaced with a current version at the same time. Combination valves used prior to 1994 are beyond the scope
of this Manual and may not be compatible with the tap.
SECTION 3 - SERVICING COMPONENTS
R. Troubleshooting Flowcharts
103
SECTION 3 - SERVICING COMPONENTS
104
SECTION 3 - SERVICING COMPONENTS
105
SECTION 3 - SERVICING COMPONENTS
106
SECTION 3 - SERVICING COMPONENTS
S. Appendices
Appendix - Instructions for Service Kit 42810-0117 Pilot/Ignitor Kit, 7/91
107
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 30185 - Pilot Tee, 3/94
108
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 30185 - Pilot Tee, 3/94
109
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 30185 - Pilot Tee, 3/94
110
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 30185 - Pilot Tee, 3/94
111
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 42810-0121 Combination Gas Valve, 1/92
112
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 42810-0121 Combination Gas Valve, 1/92
113
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 42810-0121 Combination Gas Valve, 1/92
114
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 42810-0121 Combination Gas Valve, 1/92
115
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 42810-0114 Ignition Module, 11/90
116
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 42810-0114 Ignition Module, 11/90
117
SECTION 3 - SERVICING COMPONENTS
Appendix - Position of Combination Gas Valve Components
during Burner Operation, 4/02
118
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Natural Gas to Propane, 8/00
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • USA • (847) 741-3300 • FAX (847) 741-4406
Instructions for Service Kits 42810-0119, 42810-0122, 42810-0123, 42810-0124, 43062, 44665
Gas Conversion Kit for Middleby Marshall Ovens
Natural Gas to Propane Operation
KIT COMPONENTS:
PS200
PS310/360
PS360WB
PS360WB70/EWB
PS555
PS570S
42810-0123
42810-0119
42810-0124
44665
43062
42810-0124
KIT, GAS CONVERSION, NATURAL
TO PROPANE
1 22176-0007
22176-0017
22176-0003
22176-0015
43060
22176-0015
ORIFICE, MAIN
0.1285”/3.26mm
1
0.113”/2.87mm
0.134”/3.40mm
0.152”/3.86mm
31980
0.165”/4.19mm
0.141”/3.58mm
0.152”/3.86mm
< - - - - - - - - - - - - - - - - - - - - - - - - 22174-0010 - - - - - - - - - - - - - - - - - - - - - - - - >
0.018”/0.45mm
1 22174-0009
0.038”/0.97mm/
#62 drill
22174-0009
0.038”/0.97mm/
#62 drill
22174-0009
0.038”/0.97mm/
#62 drill
22174-0009 22174-0009 *
0.038”/0.97mm/
#62 drill
0.038”/0.97mm/
#62 drill
NONE *
Description
ORIFICE, PILOT
22174-0009 * ORIFICE, BYPASS (HIGH-FLAME)
0.038”/0.97mm/
#62 drill
1
< - - - - - - - - - - - - - - - - - - - - - - - - 28092-0018 - - - - - - - - - - - - - - - - - - - - - - - - >
KIT, GAS CONTROL VALVE SPRING
- PROPANE
1
< - - - - - - - - - - - - - - - - - - - - - - - - 22500-0065 - - - - - - - - - - - - - - - - - - - - - - - - >
LABEL, PROPANE (RED)
1
< - - - - - - - - - - - - - - - - - - - - - - - - 22500-0123 - - - - - - - - - - - - - - - - - - - - - - - - >
LABEL, GAS CONVERSION
1
< - - - - - - - - - - - - - - - - - - - - - - - - 22501-0007 - - - - - - - - - - - - - - - - - - - - - - - - >
TAG, GAS CONTROL CONVERSION
1
< - - - - - - - - - - - - - - - - - - - - - - - - 88210-0069 - - - - - - - - - - - - - - - - - - - - - - - - >
INSTRUCTIONS
*
NOTE: The bypass orifice is not used if the oven is equipped with a modulating gas valve. These ovens include:
•
•
•
PS360EWB (all)
PS555 (all)
PS570S (units produced 4/00 or later)
For additional information, refer to Part III of these instructions (Bypass Orifice Conversion).
IMPORTANT
THIS CONVERSION KIT IS INTENDED FOR AGA-, CGA-, AND CSA-APPROVED MIDDLEBY
MARSHALL GAS-FIRED OVENS OPERATING AT ALTITUDES UP TO 5000 FT. (1524m).
FOR OVENS INSTALLED AT ALTITUDES ABOVE 5000 FT. (1524m), CONSULT THE FACTORY BEFORE INSTALLING THIS KIT.
THIS KIT MAY NOT BE USED WITH CE-APPROVED MIDDLEBY MARSHALL OVENS.
FOR THESE OVENS, FOLLOW THE GAS CONVERSION INSTRUCTIONS IN THE INSTALLATION SECTION OF THE OVEN’S OWNER’S OPERATING AND INSTALLATION MANUAL.
WARNING
THIS CONVERSION KIT IS TO BE INSTALLED BY A MIDDLEBY MARSHALL AUTHORIZED SERVICE AGENT
IN ACCORDANCE WITH THE MANUFACTURER’S INSTRUCTIONS AND ALL CODES AND REQUIREMENTS
OF THE AUTHORITY HAVING JURISDICTION. FAILURE TO FOLLOW INSTRUCTIONS COULD RESULT IN
SERIOUS INJURY OR PROPERTY DAMAGE. THE AUTHORIZED SERVICE AGENT PERFORMING THIS
WORK ASSUMES RESPONSIBILITY FOR THIS CONVERSION.
WARNING
BEFORE PERFORMING ANY SERVICE WORK, THE ELECTRICAL POWER SUPPLY AND THE GAS SUPPLY MUST BE TURNED OFF.
1
119
P/N 88210-0069 • Rev. C • V1 • 8/00
ENGLISH - page 1
PS220/224
1 42810-0122
ESPAÑOL - página 7
Qty.
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Natural Gas to Propane, 8/00
Typical PS200-series gas train configuration
Burner
blower
Solenoid
valve
Pilot line
Combination gas
control valve
(safety regulator)
Burner
ENGLISH
Bypass
line
Pilot pressure
tap (pilot tee)
Gas pipe union
Typical PS300-series gas train configuration
Modulating gas
valve (if so
equipped)
Burner
blower
Combination gas
control valve
(safety regulator)
Solenoid valve
(if so equipped)
Bypass
line
Burner
Gas pipe
union
Pilot line
Manual
shutoff valve
Pilot pressure tap (pilot tee)
Typical PS555 or PS570S gas train configuration
Burner
blower
Burner
Solenoid valve
(if so equipped)
Combination gas
control valve
(safety regulator)
Bypass
line
Pilot
line
Manual
shutoff valve
Gas pipe
union
Pilot pressure
tap (pilot tee)
2
120
Modulating gas
valve (if so
equipped)
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Natural Gas to Propane, 8/00
I.
PREPARATION AND DISASSEMBLY
Figure 1
1. Turn off the electric power supply to the oven.
2. Turn off the gas supply at the service valve behind the
oven.
3. Open the machinery compartment door.
Hex
screws
4. Open the union in the gas supply line. The union is
located on the inlet side of the combination gas control
valve. See Figure 1.
5. Unscrew the four hex screws that hold the venturi
mounting plate to the front of the burner. Remove the
gas train/venturi assembly from the oven.
II. COMBINATION GAS CONTROL VALVE (SAFETY
REGULATOR) CONVERSION
PS570S gas train (with solenoid valve) shown.
Refer to the illustrations on Page 2 for
component placement for other oven models.
1. Remove and discard the following components from the
combination gas control valve, as shown in Figure 2:
• Regulator cap screw
• Regulator adjustment screw
• Regulator spring
Figure 2
2. Install the red kit-supplied regulator spring, with the
tapered end facing into the valve, as shown in Figure 2.
3. Install the white kit-supplied regulator adjustment screw.
Carefully adjust the screw until its top is flush with the
top of the regulator.
4. Turn the adjustment screw six complete turns in a
clockwise direction. This preliminary pressure setting
is approximately 10-1/2” W.C. (26.1mbar).
Adjustment
screw
5. Install the black kit-supplied cap screw.
III. BYPASS ORIFICE CONVERSION
NOTE: Ovens are equipped with EITHER an on-off solenoid
valve with a separate bypass line, OR with a modulating gas
valve. Refer to the illustrations on Page 2. When installing
this Kit, the bypass orifice will only be changed if the oven
is equipped with a solenoid valve.
• If the oven is equipped with a modulating gas valve, skip
ahead to Section IV, Pilot Orifice Conversion.
• If the oven is equipped with a solenoid valve, continue on
to Step 1, below.
Regulator
spring
Cap screw
Figure 3
1. Unscrew the compression nuts at both ends of the
bypass tube, and slide them back and out of the way.
Then, remove and retain the tubing. See Figure 3.
Compression
nut
2. Remove and discard the existing bypass orifice.
3. Slip the kit-supplied bypass orifice into the discharge
end of the bypass tube, as shown in Figure 3.
4. With the orifice in place, push the tube back into the
compression fittings until it bottoms.
Bypass
orifice
5. While holding the tube in place, slide the compression
nuts into place. Tighten them to a snug fit with your
fingers.
6. Gently tighten the nuts one complete turn with a
wrench. DO NOT OVERTIGHTEN THE COMPRESSION
NUTS.
Bypass
tube
3
121
ENGLISH
Gas pipe
union
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Natural Gas to Propane, 8/00
IV. PILOT ORIFICE CONVERSION
Figure 4
1. Unscrew the two 1/2" nuts that secure the gas train to
the venturi mounting plate. See Figure 4.
Venturi
2. Unscrew the pilot tube compression nut, and slide it out
of the way. Then, pull the tube from the fitting to expose
the pilot orifice. See Figure 4.
Spark
cable
3. Separate the venturi, mounting plate, and gas train
assembly. Leave the main orifice holder attached to the
gas train piping assembly.
4. Remove and discard the existing pilot orifice.
Pilot
orifice
5. Slip the kit-supplied pilot orifice into the pilot tube.
ENGLISH
6. With the orifice in place, push the tube back into the
compression fitting until it bottoms.
7. While holding the tube in place, slide the compression
nut into place. Tighten the nut to a snug fit with your
fingers.
Compression
nut
Orifice
holder
8. Gently tighten the nut one complete turn with a wrench.
DO NOT OVERTIGHTEN THE COMPRESSION NUT.
Main
orifice
9. To allow the main orifice to be replaced, do not reassemble
the gas train to the venturi and mounting plate at this
time.
V. MAIN ORIFICE CONVERSION
1. Unscrew the existing main orifice from its holder using
an 11/16” wrench. See Figure 4.
1/2” hex nuts
2. Install the kit-supplied main orifice into the holder.
VI. REASSEMBLY
1. Check that the pilot assembly is correctly aligned with
the venturi, as shown in Figure 5. If necessary,
reposition the pilot assembly.
2. Reassemble the venturi and mounting plate to the gas
train assembly. Replace the two 1/2” hex nuts to hold
the assembly together.
3. Replace the assembled gas train into the oven. Tighten
the gas pipe union (on the inlet side of the combination
gas valve) to hold the gas train in place.
Figure 5
View from side of venturi
View from rear of venturi
Rear edge
of pilot
hood is on
centerline
of venturi
Pilot hood
11/16” (17.5mm)
3/8” (9.5mm)
4
122
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Natural Gas to Propane, 8/00
VII. GAS LEAK TEST
VIII. INLET PRESSURE CHECK
1. Restore the electrical and gas utility connections to the
oven.
1. Using a manometer, check the inlet pressure at the inlet
pressure tap. See Figure 6. An inlet pressure of 11-14”
W.C. (27.4-34.9mbar) is recommended for propane
operation.
2. Paint all gas pipe connections from the union to the
venturi mounting plate, as well as the pilot tubing,
bypass tubing, and pressure tap plug, with a rich
solution of soap and water (2/3 soap, 1/3 water is
recommended). Any visible bubbles indicate a gas
leak.
3. If a gas leak is detected, tighten the affected joints and
connections. If tightening the connection(s) fails to stop
the leak:
• Turn off the electric power supply to the oven.
• Turn off the gas supply at the service valve behind
the oven.
• Replace the affected component(s).
• Repeat the gas leak test.
CAUTION
IF IT IS NECESSARY TO ADJUST THE GAS LINE
PRESSURE, HAVE THE CUSTOMER CONTACT THE
GAS UTILITY SUPPLIER.
WARNING - FIRE/EXPLOSION HAZARD
HIDDEN GAS LEAKS CAN CAUSE A FLASHBACK
IN THE MACHINERY COMPARTMENT. THIS
CAN CAUSE SEVERE INJURY OR DEATH.
STAND WELL CLEAR WHEN SWITCHING ON
THE HEATING CIRCUIT.
IX. PILOT PRESSURE ADJUSTMENT
1. Unscrew the cap plug from the pilot pressure tap (pilot
tee), and attach a manometer to the tap. See Figure 6.
2. Remove the pilot adjustment cap screw from the
combination gas control valve.
4. If no leaks are detected by the test, depress the safety
switch(es) and switch on the oven. Then, switch on the
heating circuit to ignite the burner.
3. Turn the oven on, and allow it to heat to temperature.
Make a note of the customer’s set point temperature.
4. After the oven has heated, adjust the set point of the
oven far lower than its current (operating) temperature.
This ensures that the pilot flame will be at its lowest level
for some time.
5. With the burner in operation, paint all gas pipe joints with
the solution of soap and water.
6. If any further gas leaks are detected, shut down the
oven. Reseal and tighten the affected joints and
connections. If tightening the connection(s) fails to stop
the leak:
•
•
•
•
Continued...
Turn off the electric power supply to the oven.
Turn off the gas supply at the service valve behind
the oven.
Replace the affected component(s).
Repeat the gas leak test.
Figure 6
Adjust manifold
pressure here
(under cap screw)
Measure
manifold
pressure here
Measure inlet
pressure here
Measure pilot
pressure here
(under cap plug)
5
123
Adjust pilot
pressure here
(under cap screw)
ENGLISH
2. If the inlet pressure is:
• HIGHER THAN 14” W.C. (34.9mbar) - This pressure
may damage the combination gas control valve
(safety regulator). The gas supply pressure should
be decreased.
• LOWER THAN 11” W.C. (27.4mbar) - It may be
necessary to increase the supplied gas pressure.
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Natural Gas to Propane, 8/00
5. The pilot pressure should be adjusted as follows:
•
X. MANIFOLD PRESSURE ADJUSTMENT
The current flow between the pilot hood and the
flame sensor, when measured with a microamp
meter or multimeter, holds constant at a minimum
of 2.0 µA. See Figure 7.
1. Remove the regulator cap screw from the combination
gas control valve.
The pilot pressure as shown on the manometer is in
the range of 8-10” W.C. (19.9-24.9mbar).
2. Using a manometer, check the pressure at the manifold
pressure tap, as shown in Figure 6. A manifold pressure
of 10” W.C. (24.9mbar) is recommended for propane
operation.
Adjust the pilot pressure as necessary by turning the
pilot adjustment screw on the combination gas control
valve. Turning the screw clockwise decreases the pilot
pressure (and current flow). Turning the screw counterclockwise increases the pressure (and current flow).
3. Adjust the pressure as necessary by turning the
adjustment screw on the combination gas control valve.
Turning the screw clockwise decreases the pressure.
Turning the screw counter-clockwise increases the
pressure.
Some valves may have a burr in the pilot adjustment
portal. If you have fully tightened the adjustment screw,
and the manometer still does not register a change in
pressure, continue to tighten the screw to break through
the burr. Back the screw out until its top is flush with the
top of its hole, then tighten the screw again as necessary
to adjust the pressure. Repeat this procedure as
necessary to properly adjust the pilot pressure.
If the manifold pressure cannot be properly adjusted,
switch the oven off and allow it to cool; then, replace the
combination gas control valve. Repeat Section VII (Gas
Leak Test) before attempting to adjust the manifold
pressure again.
•
ENGLISH - page 1
4. After the manifold pressure has been properly adjusted,
replace the cap screw. Record the final value on the Gas
Conversion Label, as shown in Figure 8.
ESPAÑOL - página 7
If the pilot pressure cannot be properly adjusted, switch
the oven off and allow it to cool; then, replace the
combination gas control valve. Repeat Section VII (Gas
Leak Test) before attempting to adjust the pilot pressure
again.
5. Switch the oven off, and allow it to cool.
XI. MARKING AND LABELING
1. Print the word “PROPANE” in the space provided on the
Gas Control Conversion Tag, P/N 22501-0007. See
Figure 8. Fasten the tag onto the gas piping next to the
combination gas control valve.
6. After the pilot pressure has been properly adjusted,
replace the cap screw.
7. Reset the oven’s set point temperature to the customer’s
original settings. Leave the oven in operation to allow
the manifold pressure to be checked in the next Section
of these instructions.
2. Locate the round “NAT” label (green or yellow) on the
burner or burner motor. Attach the kit-supplied red
“LPG” label, P/N 22500-0065, on top of the “NAT” label.
The new label should completely cover the “NAT” label.
See Figure 8.
Figure 7
3. Complete the information on the Gas Conversion Label
as shown in Figure 8.
Flame sensor ( + )
4. Attach the Gas Conversion Label in plain view on the
outside of the oven, as close as possilble to the oven’s
serial plate.
Pilot hood ( - )
Figure 8
Attach on top of
existing “NAT”
label (on burner or
burner motor)
Attach to gas
piping next to
combination
gas valve
Name of
technician
Date of
conversion
New label completely
covers “NAT” label
Measured value
from Section X
Part no. of this
Kit - see chart
on Page 1
Stated on the oven’s
serial plate
6
124
See chart on
Page 1
Attach completed label in plain
view near serial plate
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Propane to Natural Gas, 8/00
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • USA • (847) 741-3300 • FAX (847) 741-4406
Instructions for Service Kits 42810-0120, 42810-0125, 42810-0126, 42810-0127, 43061, 44664
Gas Conversion Kit for Middleby Marshall Ovens
Propane to Natural Gas Operation
KIT COMPONENTS:
PS200
PS310/360
PS360WB
PS360WB70/EWB
PS555
PS570S
42810-0126
42810-0120
42810-0127
44664
43061
42810-0127
KIT, GAS CONVERSION, PROPANE
TO NATURAL
1 22176-0010
22176-0016
22176-0004
22176-0014
22176-0014
43059
22176-0014
ORIFICE, MAIN
0.204”/5.18mm
1
0.182”/4.62mm
0.219”/5.56mm
0.250”/6.35mm
0.250”/6.35mm
0.228”/5.79mm
0.250”/6.35mm
< - - - - - - - - - - - - - - - - - - - - - - - - 22174-0011 - - - - - - - - - - - - - - - - - - - - - - - - >
0.028”/0.71mm
1 22174-0006
0.060”/1.52mm/
#53 drill
22174-0006
0.060”/1.52mm/
#53 drill
22174-0006
0.060”/1.52mm/
#53 drill
22174-0006 22174-0006 *
0.060”/1.52mm/
#53 drill
0.060”/1.52mm/
#53 drill
NONE *
Description
ORIFICE, PILOT
22174-0006 * ORIFICE, BYPASS (HIGH-FLAME)
0.060”/1.52mm/
#53 drill
1
< - - - - - - - - - - - - - - - - - - - - - - - - 28092-0019 - - - - - - - - - - - - - - - - - - - - - - - - >
KIT, GAS CONTROL VALVE SPRING
- NATURAL GAS
1
< - - - - - - - - - - - - - - - - - - - - - - - - 22500-0064 - - - - - - - - - - - - - - - - - - - - - - - - >
LABEL, NATURAL GAS (YELLOW/
GREEN)
1
< - - - - - - - - - - - - - - - - - - - - - - - - 22500-0123 - - - - - - - - - - - - - - - - - - - - - - - - >
LABEL, GAS CONVERSION
1
< - - - - - - - - - - - - - - - - - - - - - - - - 22501-0007 - - - - - - - - - - - - - - - - - - - - - - - - >
TAG, GAS CONTROL CONVERSION
1
< - - - - - - - - - - - - - - - - - - - - - - - - 88210-0070 - - - - - - - - - - - - - - - - - - - - - - - - >
INSTRUCTIONS
*
NOTE: The bypass orifice is not used if the oven is equipped with a modulating gas valve. These ovens include:
•
•
•
PS360EWB (all)
PS555 (all)
PS570S (units produced 4/00 or later)
For additional information, refer to Part III of these instructions (Bypass Orifice Conversion).
IMPORTANT
THIS CONVERSION KIT IS INTENDED FOR AGA-, CGA-, AND CSA-APPROVED MIDDLEBY
MARSHALL GAS-FIRED OVENS OPERATING AT ALTITUDES UP TO 5000 FT. (1524m).
FOR OVENS INSTALLED AT ALTITUDES ABOVE 5000 FT. (1524m), CONSULT THE FACTORY BEFORE INSTALLING THIS KIT.
THIS KIT MAY NOT BE USED WITH CE-APPROVED MIDDLEBY MARSHALL OVENS.
FOR THESE OVENS, FOLLOW THE GAS CONVERSION INSTRUCTIONS IN THE INSTALLATION SECTION OF THE OVEN’S OWNER’S OPERATING AND INSTALLATION MANUAL.
WARNING
THIS CONVERSION KIT IS TO BE INSTALLED BY A MIDDLEBY MARSHALL AUTHORIZED SERVICE AGENT
IN ACCORDANCE WITH THE MANUFACTURER’S INSTRUCTIONS AND ALL CODES AND REQUIREMENTS
OF THE AUTHORITY HAVING JURISDICTION. FAILURE TO FOLLOW INSTRUCTIONS COULD RESULT IN
SERIOUS INJURY OR PROPERTY DAMAGE. THE AUTHORIZED SERVICE AGENT PERFORMING THIS
WORK ASSUMES RESPONSIBILITY FOR THIS CONVERSION.
WARNING
BEFORE PERFORMING ANY SERVICE WORK, THE ELECTRICAL POWER SUPPLY AND THE GAS SUPPLY MUST BE TURNED OFF.
1
125
P/N 88210-0070 • Rev. C • V1 • 8/00
ENGLISH - page 1
PS220/224
1 42810-0125
ESPAÑOL - página 7
Qty.
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Propane to Natural Gas, 8/00
Typical PS200-series gas train configuration
Burner
blower
Solenoid
valve
Pilot line
Combination gas
control valve
(safety regulator)
Burner
ENGLISH
Bypass
line
Pilot pressure
tap (pilot tee)
Gas pipe union
Typical PS300-series gas train configuration
Modulating gas
valve (if so
equipped)
Burner
blower
Combination gas
control valve
(safety regulator)
Solenoid valve
(if so equipped)
Bypass
line
Burner
Gas pipe
union
Pilot line
Manual
shutoff valve
Pilot pressure tap (pilot tee)
Typical PS555 or PS570S gas train configuration
Burner
blower
Burner
Solenoid valve
(if so equipped)
Combination gas
control valve
(safety regulator)
Bypass
line
Pilot
line
Manual
shutoff valve
Gas pipe
union
Pilot pressure
tap (pilot tee)
2
126
Modulating gas
valve (if so
equipped)
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Propane to Natural Gas, 8/00
I.
PREPARATION AND DISASSEMBLY
Figure 1
1. Turn off the electric power supply to the oven.
2. Turn off the gas supply at the service valve behind the
oven.
3. Open the machinery compartment door.
Hex
screws
4. Open the union in the gas supply line. The union is
located on the inlet side of the combination gas control
valve. See Figure 1.
5. Unscrew the four hex screws that hold the venturi
mounting plate to the front of the burner. Remove the
gas train/venturi assembly from the oven.
II. COMBINATION GAS CONTROL VALVE (SAFETY
REGULATOR) CONVERSION
PS570S gas train (with solenoid valve) shown.
Refer to the illustrations on Page 2 for
component placement for other oven models.
1. Remove and discard the following components from the
combination gas control valve, as shown in Figure 2:
• Regulator cap screw
• Regulator adjustment screw
• Regulator spring
Figure 2
2. Install the stainless steel kit-supplied regulator spring,
with the tapered end facing into the valve, as shown in
Figure 2.
3. Install the kit-supplied regulator adjustment screw.
Carefully adjust the screw until its top is flush with the
top of the regulator.
4. Turn the adjustment screw six complete turns in a
clockwise direction. This preliminary pressure setting
is approximately 3-1/2” W.C. (8.7mbar).
Adjustment
screw
5. Install the silver kit-supplied cap screw.
III. BYPASS ORIFICE CONVERSION
Regulator
spring
NOTE: Ovens are equipped with EITHER an on-off solenoid
valve with a separate bypass line, OR with a modulating gas
valve. Refer to the illustrations on Page 2. When installing
this Kit, the bypass orifice will only be changed if the oven
is equipped with a solenoid valve.
• If the oven is equipped with a modulating gas valve, skip
ahead to Section IV, Pilot Orifice Conversion.
• If the oven is equipped with a solenoid valve, continue on
to Step 1, below.
Cap screw
Figure 3
1. Unscrew the compression nuts at both ends of the
bypass tube, and slide them back and out of the way.
Then, remove and retain the tubing. See Figure 3.
Compression
nut
2. Remove and discard the existing bypass orifice.
3. Slip the kit-supplied bypass orifice into the discharge
end of the bypass tube, as shown in Figure 3.
Bypass
orifice
4. With the orifice in place, push the tube back into the
compression fittings until it bottoms.
5. While holding the tube in place, slide the compression
nuts into place. Tighten them to a snug fit with your
fingers.
6. Gently tighten the nuts one complete turn with a
wrench. DO NOT OVERTIGHTEN THE COMPRESSION
NUTS.
Bypass
tube
3
127
ENGLISH
Gas pipe
union
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Propane to Natural Gas, 8/00
IV. PILOT ORIFICE CONVERSION
Figure 4
1. Unscrew the two 1/2" nuts that secure the gas train to
the venturi mounting plate. See Figure 4.
Venturi
2. Unscrew the pilot tube compression nut, and slide it out
of the way. Then, pull the tube from the fitting to expose
the pilot orifice. See Figure 4.
Spark
cable
3. Separate the venturi, mounting plate, and gas train
assembly. Leave the main orifice holder attached to the
gas train piping assembly.
4. Remove and discard the existing pilot orifice.
Pilot
orifice
5. Slip the kit-supplied pilot orifice into the pilot tube.
ENGLISH
6. With the orifice in place, push the tube back into the
compression fitting until it bottoms.
7. While holding the tube in place, slide the compression
nut into place. Tighten the nut to a snug fit with your
fingers.
Compression
nut
Orifice
holder
8. Gently tighten the nut one complete turn with a wrench.
DO NOT OVERTIGHTEN THE COMPRESSION NUT.
Main
orifice
9. To allow the main orifice to be replaced, do not reassemble
the gas train to the venturi and mounting plate at this
time.
V. MAIN ORIFICE CONVERSION
1. Unscrew the existing main orifice from its holder using
an 11/16” wrench. See Figure 4.
1/2” hex nuts
2. Install the kit-supplied main orifice into the holder.
VI. REASSEMBLY
1. Check that the pilot assembly is correctly aligned with
the venturi, as shown in Figure 5. If necessary,
reposition the pilot assembly.
2. Reassemble the venturi and mounting plate to the gas
train assembly. Replace the two 1/2” hex nuts to hold
the assembly together.
3. Replace the assembled gas train into the oven. Tighten
the gas pipe union (on the inlet side of the combination
gas valve) to hold the gas train in place.
Figure 5
View from side of venturi
View from rear of venturi
Rear edge
of pilot
hood is on
centerline
of venturi
Pilot hood
11/16” (17.5mm)
3/8” (9.5mm)
4
128
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Propane to Natural Gas, 8/00
VII. GAS LEAK TEST
VIII. INLET PRESSURE CHECK
1. Restore the electrical and gas utility connections to the
oven.
1. Using a manometer, check the inlet pressure at the inlet
pressure tap. See Figure 6. An inlet pressure of 6-12”
W.C. (14.9-29.9mbar) is recommended for natural gas
operation.
2. Paint all gas pipe connections from the union to the
venturi mounting plate, as well as the pilot tubing,
bypass tubing, and pressure tap plug, with a rich
solution of soap and water (2/3 soap, 1/3 water is
recommended). Any visible bubbles indicate a gas
leak.
3. If a gas leak is detected, tighten the affected joints and
connections. If tightening the connection(s) fails to stop
the leak:
• Turn off the electric power supply to the oven.
• Turn off the gas supply at the service valve behind
the oven.
• Replace the affected component(s).
• Repeat the gas leak test.
CAUTION
IF IT IS NECESSARY TO ADJUST THE GAS LINE
PRESSURE, HAVE THE CUSTOMER CONTACT THE
GAS UTILITY SUPPLIER.
WARNING - FIRE/EXPLOSION HAZARD
HIDDEN GAS LEAKS CAN CAUSE A FLASHBACK
IN THE MACHINERY COMPARTMENT. THIS
CAN CAUSE SEVERE INJURY OR DEATH.
STAND WELL CLEAR WHEN SWITCHING ON
THE HEATING CIRCUIT.
IX. PILOT PRESSURE ADJUSTMENT
1. Unscrew the cap plug from the pilot pressure tap (pilot
tee), and attach a manometer to the tap. See Figure 6.
2. Remove the pilot adjustment cap screw from the
combination gas control valve.
4. If no leaks are detected by the test, depress the safety
switch(es) and switch on the oven. Then, switch on the
heating circuit to ignite the burner.
3. Turn the oven on, and allow it to heat to temperature.
Make a note of the customer’s set point temperature.
4. After the oven has heated, adjust the set point of the
oven far lower than its current (operating) temperature.
This ensures that the pilot flame will be at its lowest level
for some time.
5. With the burner in operation, paint all gas pipe joints with
the solution of soap and water.
6. If any further gas leaks are detected, shut down the
oven. Reseal and tighten the affected joints and
connections. If tightening the connection(s) fails to stop
the leak:
•
•
•
•
Continued...
Turn off the electric power supply to the oven.
Turn off the gas supply at the service valve behind
the oven.
Replace the affected component(s).
Repeat the gas leak test.
Figure 6
Adjust manifold
pressure here
(under cap screw)
Measure
manifold
pressure here
Measure inlet
pressure here
Measure pilot
pressure here
(under cap plug)
5
129
Adjust pilot
pressure here
(under cap screw)
ENGLISH
2. If the inlet pressure is:
• HIGHER THAN 14” W.C. (34.9mbar) - This pressure
may damage the combination gas control valve
(safety regulator). The gas supply pressure should
be decreased.
• LOWER THAN 6” W.C. (14.9mbar) - It may be
necessary to increase the supplied gas pressure.
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for All Gas Conversion Kits
for Ovens with Wayne Burner, Propane to Natural Gas, 8/00
5. The pilot pressure should be adjusted as follows:
•
X. MANIFOLD PRESSURE ADJUSTMENT
The current flow between the pilot hood and the
flame sensor, when measured with a microamp
meter or multimeter, holds constant at a minimum
of 2.0 µA. See Figure 7.
1. Remove the regulator cap screw from the combination
gas control valve.
The pilot pressure as shown on the manometer is in
the range of 3-1/2” - 4” W.C. (8.7-10.0 mbar).
2. Using a manometer, check the pressure at the manifold
pressure tap, as shown in Figure 6. A manifold pressure
of 3-1/2” W.C. (8.7mbar) is recommended for natural
gas operation.
Adjust the pilot pressure as necessary by turning the
pilot adjustment screw on the combination gas control
valve. Turning the screw clockwise decreases the pilot
pressure. Turning the screw counter-clockwise increases
the pressure.
3. Adjust the pressure as necessary by turning the
adjustment screw on the combination gas control valve.
Turning the screw clockwise decreases the pressure.
Turning the screw counter-clockwise increases the
pressure.
Some valves may have a burr in the pilot adjustment
portal. If you have fully tightened the adjustment screw,
and the manometer still does not register a change in
pressure, continue to tighten the screw to break through
the burr. Back the screw out until its top is flush with the
top of its hole, then tighten the screw again as necessary
to adjust the pressure. Repeat this procedure as
necessary to properly adjust the pilot pressure.
If the manifold pressure cannot be properly adjusted,
switch the oven off and allow it to cool; then, replace the
combination gas control valve. Repeat Section VII (Gas
Leak Test) before attempting to adjust the manifold
pressure again.
•
ENGLISH - page 1
4. After the manifold pressure has been properly adjusted,
replace the cap screw. Record the final value on the Gas
Conversion Label, as shown in Figure 8.
ESPAÑOL - página 7
If the pilot pressure cannot be properly adjusted, switch
the oven off and allow it to cool; then, replace the
combination gas control valve. Repeat Section VII (Gas
Leak Test) before attempting to adjust the pilot pressure
again.
5. Switch the oven off, and allow it to cool.
XI. MARKING AND LABELING
1. Print the word “NATURAL” in the space provided on the
Gas Control Conversion Tag, P/N 22501-0007. See
Figure 8. Fasten the tag onto the gas piping next to the
combination gas control valve.
7. After the pilot pressure has been properly adjusted,
replace the cap screw.
8. Reset the oven’s set point temperature to the customer’s
original settings. Leave the oven in operation to allow
the manifold pressure to be checked in the next Section
of these instructions.
2. Locate the round “LPG” label (red) on the burner or
burner motor. Attach the kit-supplied yellow/green
“NAT” label, P/N 22500-0064, on top of the “LPG” label.
The new label should completely cover the “LPG” label.
See Figure 8.
Figure 7
Flame sensor ( + )
3. Complete the information on the Gas Conversion Label
as shown in Figure 8.
4. Attach the Gas Conversion Label in plain view on the
outside of the oven, as close as possilble to the oven’s
serial plate.
Pilot hood ( - )
Figure 8
Attach on top of
existing “LPG”
label (on burner or
burner motor)
Attach to gas
piping next to
combination
gas valve
Name of
technician
Date of
conversion
New label completely
covers “LPG” label
Measured value
from Section X
Part no. of this
Kit - see chart
on Page 1
Stated on the oven’s
serial plate
6
130
See chart on
Page 1
Attach completed label in plain
view near serial plate
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 36856 - Gas Conversion Kit for
PS360EWB/WB70 with Midco Burner, Natural Gas to Propane, 1/98
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • (847)741-3300 • FAX (847)741-4406
Middleby
Marshall®
Oven Gas Conversion Kit p/n 36856
PS360EWB and PS360WB70
Natural Gas to Propane Installation Instructions
WARNING
This conversion kit is to be installed by a Middleby Marshall Authorized Service Organization in accordance with
the manufacturer’s instructions and all codes and requirements of the authority having jurisdiction. Failure to
follow instructions could result in serious injury or property damage. The authorized service organization
performing this work assumes responsibility for this conversion.
This kit consists of the following parts:
Qty.
Units
p/n
Description
1
ea.
36857
1
1
ea.
ea.
31819
31822
1
1
ea.
ea.
22174-0009
22500-0065
1
ea.
22500-0123
Instructions for Conversion of Natural Gas Operation to Propane Operation, PS360EWB and
PS360WB70
Orifice, Pilot Assembly - Propane, 0.025” (0.64mm)
Orifice, Main - Propane, 0.185” (4.70mm)
Orifice, Low Flame - Propane, 0.034” (0.86mm, #62 drill) - used for converting PS360WB70 only
Label, LPG, Red
Label, Conversion - Gas
IMPORTANT
When converting any oven that is installed at an altitude above 5000 ft. (1524m), consult Middleby before installing
this Kit.
1. PREPARATION
1.1 Turn off the electric power supply to the oven.
1.2 Turn off the gas supply at the service valve behind the oven.
WARNING
Before performing any service or conversion work, the electrical power supply AND the gas supply MUST be
turned off.
1.3 Open the machinery compartment access door.
2. PILOT ORIFICE REPLACEMENT
2.1 Unscrew the brass fittings at both ends of the aluminum pilot tubing that connects the pilot orifice to the combination gas control
valve. This allows the tubing to be removed. See Figure 1.
Figure 1
Conversion component locations
Solenoid valve
(PS360WB70 only)
Main
orifice
holder
Low flame bypass
(PS360WB70 only)
Combination gas
control valve
Pilot
orifice
Aluminum
pilot tubing
p/n 36857
P. Jan 98 Rev. B
131
Page 1 of 4
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 36856 - Gas Conversion Kit for
PS360EWB/WB70 with Midco Burner, Natural Gas to Propane, 1/98
2.2 Remove and retain the aluminum pilot tubing from the burner
assembly. The end of the tubing that enters the combination gas
control valve should be removed first.
2.3 Remove and retain the pilot orifice by unscrewing it (counterclockwise)
from the burner plenum wall.
Figure 2
Pilot orifice assembly
Pilot tubing connector
2.4 Unscrew and retain the pilot tubing connector and the pilot tap plug
from the ends of the pilot orifice, as shown in Figure 2. When these
attachments have been removed, discard the pilot orifice.
2.5 Screw the pilot tubing connector and the pilot tap plug into place in
the new propane pilot orifice (p/n 31819). Tighten them to a snug fit.
2.6 Screw the new propane pilot orifice into its opening in the plenum
wall. Tighten it to a snug fit. Ensure that the end of the orifice holding
the pilot tubing mount points towards the piping assembly.
Pilot tap plug
Pilot orifice
Figure 3
Main orifice and holder
Main orifice
holder
2.7 Replace the aluminum pilot tubing that was removed in Step 2.2, above.
2.8 Screw in the brass fittings at both ends of the aluminum pilot tubing.
Tighten them to a snug fit. DO NOT OVERTIGHTEN THE FITTINGS.
3. MAIN ORIFICE REPLACEMENT
Main orifice
3.1 Remove and retain the main orifice holder by unscrewing it
(counterclockwise) from the burner plenum wall.
Main manifold tap
plug (leave in place)
3.2 Unscrew and discard the main orifice from the inner end of the holder,
as shown in Figure 3.
3.3 Screw the new propane main orifice (p/n 31822) into the orifice holder.
Tighten it to a snug fit.
3.4 Replace the main orifice holder into its opening in the burner plenum.
Tighten it to a snug fit.
Figure 4
Low flame orifice replacement
4. LOW FLAME ORIFICE REPLACEMENT (PS360WB70 only)
Aluminum
tubing
4.1 Unscrew the brass fittings at both ends of the aluminum low flame
tubing. This allows the tubing to be removed. See Figure 4.
4.2 Remove and retain the tubing from the solenoid valve.
4.3 Remove and discard the low flame orifice from the end of the low
flame tubing.
Low flame
orifice
u
To b
rn e r
4.4 Insert the new propane low flame orifice (p/n 22174-0009) into the
discharge end of the low flame tubing, as shown in Figure 4.
4.5 Replace the low flame tubing into the fittings on the solenoid valve.
4.6 Screw in the brass fittings at both ends of the aluminum low flame
tubing. Tighten them to a snug fit.
tion
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ga
Solenoid valve
5. GAS LEAK TEST
5.1 Paint all pipe connections from the gas union to the burner plenum, and the aluminum pilot and low flame orifice tubing connections,
with a solution of soap and water (2/3 soap, 1/3 water is recommended). Any bubbles that are visible indicate a gas leak.
5.2 If a gas leak is detected, tighten the affected joints and connections. If tightening the connections fails to stop the leak, replace
the affected component and repeat the gas leak test.
WARNING - FIRE / EXPLOSION HAZARD
Hidden gas leaks can cause a flashback in the machinery compartment. THIS CAN CAUSE SEVERE INJURY OR
DEATH. Stand well clear when switching on the heating circuit.
5.3 If no leaks are detected by the test, switch on the oven. Switch on the heating circuit to ignite the main burner.
5.4 With the burner in operation, paint all gas pipe joints with the solution of soap and water.
5.5 If any further gas leaks are detected, shut down the oven. Reseal and tighten the affected joints and connections. If tightening
the connections fails to stop the leak, replace the affected component(s) and repeat the gas leak test.
Page 2 of 4
P. Jan 98 Rev. B
132
p/n 36857
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 36856 - Gas Conversion Kit for
PS360EWB/WB70 with Midco Burner, Natural Gas to Propane, 1/98
6. INLET PRESSURE CHECK
6.1 Check the gas control inlet pressure at the inlet pressure tap. See Figure 6. An inlet pressure of 6-14” (14.9-34.9mbar) is
recommended for propane operation.
6.2 If the inlet pressure is:
•
HIGHER THAN 14” W. C. (34.9mbar) - This pressure may damage the combination gas control valve. Decrease the supplied
gas pressure.
•
LOWER THAN 3” W. C. (7.46mbar) - It may be necessary to increase the supplied gas pressure.
If it is necessary to adjust the gas line pressure, have the customer contact the gas utility supplier.
7. PILOT PRESSURE ADJUSTMENT
7.1 Ensure that the air supply is properly adjusted for propane operation.
•
Units with a burner blower air shutter (see Figure 5) should have the shutter opening (at its outside edge) set to 5/16”
(7.94mm). A drill bit can be used to check the adjustment of this opening.
•
Units without the air shutter (see Figure 5) should have the burner air supply adjustment screw turned 11-17 full revolutions
clockwise from the fully closed (counterclockwise) position. The screw is located on the front wall of the burner plenum, and
is surrounded by a “MORE AIR” label.
Figure 5
Insert a 5/16”
(7.94mm) drill
bit to measure
opening
(remove before
operation)
Burner blower configurations
External
air
shutter
7.2 Before proceeding:
•
For a PS360EWB oven, the set point should be reduced
below the room temperature.
•
For a PS360WB70 oven, set the oven to low flame.
7.3 Measure the pilot pressure at the pilot pressure tap, as shown
in Figure 6. The gas pressure should be 5-6” W. C. (12.514.9mbar) for proper operation.
7.4 If necessary, adjust the pilot pressure as follows:
•
•
•
Remove the pilot adjustment cap screw.
Using a screwdriver, turn the inner adjustment screw
counterclockwise to increase, or clockwise to decrease,
the pilot gas pressure.
Replace the cap screw and tighten it firmly.
7.5 Measure the current across the pilot flame sensor. The
current must measure at least 2.0 µA. If the current reading
is too low, recheck the pilot pressure as per Step 7.3. If the
pressure reading is correct, consult the factory; otherwise,
repeat Steps 7.4 and 7.5.
Blowers without
external air shutter
OR
Figure 6
Gas pressure measurement/adjustment locations
Pressure
regulator cap
screw
Pilot tube
connects
here
Pilot
adjustment
cap screw
Inlet pressure
tap
Main orifice
pressure tap
8. MAIN MANIFOLD PRESSURE ADJUSTMENT
8.1 With the oven set to high flame, measure the regulated gas
pressure to the burner. The outlet pressure should be
checked at the main orifice pressure tap. See Figure 6.
The gas pressure should be 3” W. C. (7.46mbar) for proper
operation.
Pilot pressure
tap
8.2 If necessary, adjust the pressure regulator as follows:
•
Remove the pressure regulator cap screw.
•
Using a screwdriver, turn the inner adjustment screw clockwise to increase, or counterclockwise to decrease, the main
burner gas pressure.
•
Replace the cap screw and tighten it firmly.
8.3 Record the final measured regulated gas pressure on the silver conversion information label (included in the kit).
p/n 36857
P. Jan 98 Rev. B
133
Page 3 of 4
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 36856 - Gas Conversion Kit for
PS360EWB/WB70 with Midco Burner, Natural Gas to Propane, 1/98
9. CONVERSION LABELING
Figure 7
Red “LPG.” label placement
(on burner housing)
9.1 Remove and discard the round, green “NAT.” label from the
front face of the burner plenum.
9.2 Apply the round, red “LPG.” label (p/n 22500-0065) to the front
face of the burner housing as shown in Figure 7.
9.3 Close the machinery compartment access door.
9.4 Record the information requested on the silver conversion
information label. Figure 8 shows a representation of this label.
9.5 Apply the conversion information label to the front of the
machinery compartment access door, next to the control panel.
See Figure 9.
Upper oven
label location
Lower oven
label location
Figure 8
Conversion information label
Signature of technician
performing conversion
Date of conversion
PROPANE
THIS APPLIANCE HAS BEEN CONVERTED ON _______________ TO ______________
GAS WITH KIT
36856
NO. ________________
BY _______________ , WHO ACCEPTS THE RESPONSIBILITY FOR
THE CORRECTNESS OF THIS CONVERSION.
MODEL NO.
MAIN BURNER ORIFICE SIZE .185”/4.70mm MANIFOLD PRESSURE
175,000
BTU
INPUT RATING
MAXIMUM INLET PRESSURES 14” W.C./34.9mbar
Measured value
recorded in Step 8.3
Stated on the
oven’s data plate
Figure 9
Conversion information label placement
THIS APPLIANCE HAS BEEN CONVERTED ON _______________ TO ______________ GAS WITH KIT
NO. ________________ BY _______________ , WHO ACCEPTS THE RESPONSIBILITY FOR
THE CORRECTNESS OF THIS CONVERSION.
MODEL NO.
INPUT RATING
MAIN BURNER ORIFICE SIZE
MAXIMUM INLET PRESSURES
MANIFOLD PRESSURE
PS360EWB placement
THIS APPLIANCE HAS BEEN CONVERTED ON _______________ TO ______________ GAS WITH KIT
NO. ________________ BY _______________ , WHO ACCEPTS THE RESPONSIBILITY FOR
THE CORRECTNESS OF THIS CONVERSION.
MODEL NO.
INPUT RATING
MAIN BURNER ORIFICE SIZE
MAXIMUM INLET PRESSURES
MANIFOLD PRESSURE
PS360WB70 placement
Page 4 of 4
P. Jan 98 Rev. B
134
p/n 36857
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 36863 - Gas Conversion Kit for
PS360EWB/WB70 with Midco Burner, Propane to Natural Gas, 1/98
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • (847)741-3300 • FAX (847)741-4406
Middleby
Marshall®
Oven Gas Conversion Kit p/n 36863
PS360EWB and PS360WB70
Propane to Natural Gas Installation Instructions
WARNING
This conversion kit is to be installed by a Middleby Marshall Authorized Service Organization in accordance with
the manufacturer’s instructions and all codes and requirements of the authority having jurisdiction. Failure to
follow instructions could result in serious injury or property damage. The authorized service organization
performing this work assumes responsibility for this conversion.
This kit consists of the following parts:
Qty.
Units
p/n
Description
1
ea.
36862
1
1
ea.
ea.
31818
31821
1
1
ea.
ea.
22174-0006
22500-0064
1
ea.
22500-0123
Instructions for Conversion of Propane Operation to Natural Gas Operation, PS360EWB and
PS360WB70
Orifice, Pilot Assembly - Natural Gas, 0.032” (0.81mm)
Orifice, Main - Natural Gas, 0.234” (5.94mm)
Orifice, Low Flame - Nat. Gas, 0.065” (1.65mm, #53 drill) - used for converting PS360WB70 only
Label, NAT, Green
Label, Conversion - Gas
IMPORTANT
When converting any oven that is installed at an altitude above 5000 ft. (1524m), consult Middleby before installing
this Kit.
1. PREPARATION
1.1 Turn off the electric power supply to the oven.
1.2 Turn off the gas supply at the service valve behind the oven.
WARNING
Before performing any service or conversion work, the electrical power supply AND the gas supply MUST be
turned off.
1.3 Open the machinery compartment access door.
2. PILOT ORIFICE REPLACEMENT
2.1 Unscrew the brass fittings at both ends of the aluminum pilot tubing that connects the pilot orifice to the combination gas control
valve. This allows the tubing to be removed. See Figure 1.
Figure 1
Conversion component locations
Solenoid valve
(PS360WB70 only)
Main
orifice
holder
Low flame bypass
(PS360WB70 only)
Combination gas
control valve
Pilot
orifice
Aluminum
pilot tubing
p/n 36862
P. Jan. 98 Rev B
135
Page 1 of 4
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 36863 - Gas Conversion Kit for
PS360EWB/WB70 with Midco Burner, Propane to Natural Gas, 1/98
2.2 Remove and retain the aluminum pilot tubing from the burner
assembly. The end of the tubing that enters the combination gas
control valve should be removed first.
2.3 Remove and retain the pilot orifice by unscrewing it (counterclockwise)
from the burner plenum wall.
Figure 2
Pilot orifice assembly
Pilot tubing connector
Pilot tap plug
2.4 Unscrew and retain the pilot tubing connector and the pilot tap plug
from the ends of the pilot orifice, as shown in Figure 2. When these
attachments have been removed, discard the pilot orifice.
Pilot orifice
2.5 Screw the pilot tubing connector and the pilot tap plug into place in
the new propane pilot orifice (p/n 31819). Tighten them to a snug fit.
2.6 Screw the new propane pilot orifice into its opening in the plenum
wall. Tighten it to a snug fit. Ensure that the end of the orifice holding
the pilot tubing mount points towards the piping assembly.
Figure 3
Main orifice and holder
Main orifice
holder
2.7 Replace the aluminum pilot tubing that was removed in Step 2.2, above.
2.8 Screw in the brass fittings at both ends of the aluminum pilot tubing.
Tighten them to a snug fit. DO NOT OVERTIGHTEN THE FITTINGS.
3. MAIN ORIFICE REPLACEMENT
Main orifice
3.1 Remove and retain the main orifice holder by unscrewing it
(counterclockwise) from the burner plenum wall.
Main manifold tap
plug (leave in place)
3.2 Unscrew and discard the main orifice from the inner end of the holder,
as shown in Figure 3.
3.3 Screw the new natural gas main orifice (p/n 31821) into the orifice
holder. Tighten it to a snug fit.
3.4 Replace the main orifice holder into its opening in the burner plenum.
Tighten it to a snug fit.
Figure 4
Low flame orifice replacement
4. LOW FLAME ORIFICE REPLACEMENT (PS360WB70 only)
Aluminum
tubing
4.1 Unscrew the brass fittings at both ends of the aluminum low flame
tubing. This allows the tubing to be removed. See Figure 4.
4.2 Remove and retain the tubing from the solenoid valve.
4.3 Remove and discard the low flame orifice from the end of the low
flame tubing.
Low flame
orifice
u
To b
rn e r
4.4 Insert the new natural gas low flame orifice (p/n 22174-0006) into the
discharge end of the low flame tubing, as shown in Figure 4.
4.5 Replace the low flame tubing into the fittings on the solenoid valve.
4.6 Screw in the brass fittings at both ends of the aluminum low flame
tubing. Tighten them to a snug fit.
tion
bina e
com
alv
From ontrol v
c
s
ga
Solenoid valve
5. GAS LEAK TEST
5.1 Paint all pipe connections from the gas union to the burner plenum, and the aluminum pilot and low flame orifice tubing connections,
with a solution of soap and water (2/3 soap, 1/3 water is recommended). Any bubbles that are visible indicate a gas leak.
5.2 If a gas leak is detected, tighten the affected joints and connections. If tightening the connections fails to stop the leak, replace
the affected component and repeat the gas leak test.
WARNING - FIRE / EXPLOSION HAZARD
Hidden gas leaks can cause a flashback in the machinery compartment. THIS CAN CAUSE SEVERE INJURY OR
DEATH. Stand well clear when switching on the heating circuit.
5.3 If no leaks are detected by the test, switch on the oven. Switch on the heating circuit to ignite the main burner.
5.4 With the burner in operation, paint all gas pipe joints with the solution of soap and water.
5.5 If any further gas leaks are detected, shut down the oven. Reseal and tighten the affected joints and connections. If tightening
the connections fails to stop the leak, replace the affected component(s) and repeat the gas leak test.
Page 2 of 4
P. Jan. 98 Rev B
136
p/n 36862
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 36863 - Gas Conversion Kit for
PS360EWB/WB70 with Midco Burner, Propane to Natural Gas, 1/98
6. INLET PRESSURE CHECK
6.1 Check the gas control inlet pressure at the inlet pressure tap. See Figure 6. An inlet pressure of 6-14” (14.9-34.9mbar) is
recommended for natural gas operation.
6.2 If the inlet pressure is:
•
HIGHER THAN 14” W. C. (34.9mbar) - This pressure may damage the combination gas control valve. Decrease the supplied
gas pressure.
•
LOWER THAN 3” W. C. (7.46mbar) - It may be necessary to increase the supplied gas pressure.
If it is necessary to adjust the gas line pressure, have the customer contact the gas utility supplier.
7. PILOT PRESSURE ADJUSTMENT
7.1 Ensure that the main burner primary air supply is properly adjusted for natural gas operation.
•
Units with a burner blower air shutter (see Figure 5) should have the shutter opening (at its outside edge) set to 5/16”
(7.94mm). A drill bit can be used to check the adjustment of this opening.
•
Units without the air shutter (see Figure 5) should have the burner air supply adjustment screw turned 11-17 full revolutions
clockwise from the fully closed (counterclockwise) position. The screw is located on the front wall of the burner plenum, and
is surrounded by a “MORE AIR” label.
Figure 5
Insert a 5/16”
(7.94mm) drill
bit to measure
opening
(remove before
operation)
Burner blower configurations
Blowers without
external air shutter
External
air
shutter
7.2 Before proceeding:
•
For a PS360EWB oven, the set point should be reduced
below the room temperature.
•
For a PS360WB70 oven, set the oven to low flame.
7.3 Measure the pilot pressure as shown in Figure 6. The gas
pressure should be 5-6” W. C. (12.5-14.9mbar) for proper
operation.
7.4 If necessary, adjust the pilot pressure as follows:
•
Remove the pilot adjustment cap screw.
•
Using a screwdriver, turn the inner adjustment screw
counterclockwise to increase, or clockwise to decrease,
the pilot gas pressure.
•
Replace the cap screw and tighten it firmly.
OR
Figure 6
Gas pressure measurement/adjustment locations
Pressure
regulator cap
screw
Pilot tube
connects
here
Inlet pressure
tap
Pilot
adjustment
cap screw
7.5 Measure the current across the pilot flame sensor. The
current must measure at least 2.0 µA. If the current reading
is too low, recheck the pilot pressure as per Step 7.3. If the
pressure reading is correct, consult the factory; otherwise,
repeat Steps 7.4 and 7.5.
Main orifice
pressure tap
8. MAIN MANIFOLD PRESSURE ADJUSTMENT
8.1 With the oven set to high flame, measure the regulated gas
pressure to the burner. The outlet pressure should be
checked at the main orifice pressure tap. See Figure 6.
The gas pressure should be 3” W. C. (7.46mbar) for proper
operation.
Pilot pressure
tap
8.2 If necessary, adjust the pressure regulator as follows:
•
•
•
Remove the pressure regulator cap screw.
Using a screwdriver, turn the inner adjustment screw clockwise to increase, or counterclockwise to decrease, the main
burner gas pressure.
Replace the cap screw and tighten it firmly.
8.3 Record the final measured regulated gas pressure on the silver conversion information label (included in the kit).
p/n 36862
P. Jan. 98 Rev B
137
Page 3 of 4
SECTION 3 - SERVICING COMPONENTS
Appendix - Instructions for Service Kit 36863 - Gas Conversion Kit for
PS360EWB/WB70 with Midco Burner, Propane to Natural Gas, 1/98
9. CONVERSION LABELING
Figure 7
Yellow “NAT.” label placement
(on burner housing)
9.1 Remove and discard the round, red “LPG.” label from the front
face of the burner plenum.
9.2 Apply the round, green “NAT.” label (p/n 22500-0064) to the
front face of the burner housing as shown in Figure 7.
9.3 Close the machinery compartment access door.
9.4 Record the information requested on the silver conversion
information label. Figure 8 shows a representation of this label.
9.5 Apply the conversion information label to the front of the
machinery compartment access door, next to the control panel.
See Figure 9.
Upper oven
label location
Lower oven
label location
Figure 8
Conversion information label
Signature of technician
performing conversion
Date of conversion
NATURAL
THIS APPLIANCE HAS BEEN CONVERTED ON _______________ TO ______________
GAS WITH KIT
36863
NO. ________________
BY _______________ , WHO ACCEPTS THE RESPONSIBILITY FOR
THE CORRECTNESS OF THIS CONVERSION.
MODEL NO.
MAIN BURNER ORIFICE SIZE .234”/5.94mm MANIFOLD PRESSURE
175,000
BTU
INPUT RATING
MAXIMUM INLET PRESSURES 14” W.C./34.9mbar
Measured value
recorded in Step 8.3
Stated on the
oven’s data plate
Figure 9
Conversion information label placement
THIS APPLIANCE HAS BEEN CONVERTED ON _______________ TO ______________ GAS WITH KIT
NO. ________________ BY _______________ , WHO ACCEPTS THE RESPONSIBILITY FOR
THE CORRECTNESS OF THIS CONVERSION.
MODEL NO.
INPUT RATING
MAIN BURNER ORIFICE SIZE
MAXIMUM INLET PRESSURES
MANIFOLD PRESSURE
PS360EWB placement
THIS APPLIANCE HAS BEEN CONVERTED ON _______________ TO ______________ GAS WITH KIT
NO. ________________ BY _______________ , WHO ACCEPTS THE RESPONSIBILITY FOR
THE CORRECTNESS OF THIS CONVERSION.
MODEL NO.
INPUT RATING
MAIN BURNER ORIFICE SIZE
MAXIMUM INLET PRESSURES
MANIFOLD PRESSURE
PS360WB70 placement
Page 4 of 4
P. Jan. 98 Rev B
138
p/n 36862
SECTION 3 - SERVICING COMPONENTS
Appendix - Equivalent Orifice Sizes at High Altitudes
(Includes 4% reduction for each 1000 ft. above sea level), 4/02
139
SECTION 3 - SERVICING COMPONENTS
2. Part number reference
XI. ELECTRIC OVEN HEATING SYSTEM
A. PS200-series ovens
Part No.
1. Description of heating system
Description
27375-0001
Heating element, 208V
All PS200-series electric ovens use an on-off system
for heater activation. When the oven demands heat,
the temperature controller activates contactors that in
turn activate the heaters at 100% power. The contactors
open when the temperature rises to 2 degrees above
the set point, and close when the oven’s temperature
falls 2 degrees Fahrenheit below the set point. Because of residual heat within the oven, however, the
temperature swing after preheating is about 5 degrees
Fahrenheit above and below the set point.
27375-0002
Heating element, 240V
27375-0003
Heating element, 380V
28041-0015
Mercury contactor, 3 pole, 50A
IMPORTANT: Because the PS200-series electric oven uses an on-off system for heater activation, the temperature controller MUST be
set to the on-off operating mode. Refer to Temperature Controller on Page 30.
31463
Relay, solid state, 75A
35018
Circuit breaker block, 50A, 3 pole
42810-0091
Contactor tube replacement kit (inc.
qty. 1 retainer clip P/N 27170-0248)
42810-0090
Coil replacement kit (inc. qty. 3 retainer clip P/N 27170-0248)
28150-0130
Fuse, 50A, class T
3. Supply
Early PS200-series ovens used mercury contactors.
208-380V ovens used two 3-pole contactors. 416-480V
ovens used a single 3-pole contactor. Six 50A fuses
(one per element) protect the heating circuit. See Figure 76.
Current PS200-series ovens replace the mercury
contactors with solid state relays mounted on heat
sinks. Six relays are used on 208-380V ovens. 416480V ovens use three relays. Ovens that use the solid
state relays also use 50A circuit breaker blocks in place
of the fuses. See Figure 77.
NOTE: All control wire used on these ovens is
rated at 221°F/105°C. DO NOT replace with lower
rated wire.
Ovens have a 208V, 220-240V, 380V, 416V or 480VAC
electrical supply. The control current of the oven operates at 110V, single phase. If the oven was specified
for a 3 wire system, it was supplied with an optional
control transformer to step the 3 phase current down
for the control circuit. If the oven was specified for a 4
wire system, the 4th (neutral) wire is utilized to split 2
of the 3 incoming 3 phase legs and obtain a separate
110V circuit. Most export ovens are supplied with a
stepdown transformer for the 110V control voltage.
Figure 77
PS200 electric (current) with solid state
relays and circuit breaker blocks
Figure 76
PS200 electric (early) with mercury
contactors and fuses
Mercury
contactor
Circuit breaker
block with 50A
breakers
Terminal
block
Solid state
relay
Fuseblock
with 50A
fuses
140
SECTION 3 - SERVICING COMPONENTS
It is also possible to check for an open element using
an ampmeter. Any current through the element indicates that the element is not open.
4. Heater specifications
•
PS200-series electric ovens use six individual heating elements.
•
208V elements are used for ovens with a 208V
supply.
•
240 volt elements are used for ovens with a 220, 230
or 240V supply. 240V elements are also used on
ovens with a 416V or 480V supply (connected in series).
•
380V elements are used for ovens with a 380V
supply.
•
All heaters are connected in Delta.
•
Each heating element is stainless clad and has a
3”/76mm cold (unheated) end next to the connecting leg.
•
6. Changing Heating Elements
Individual element electrical data
Volts
Watts
Ohms
Connection
208V
220V
230V
240V
380V
416V
480V
4500W
3781W
4133W
4500W
4500W
3380W
4500W
9.6W
12.8W
12.8W
12.8W
32.2W
12.8W
12.8W
Parallel
Parallel
Parallel
Parallel
Parallel
Series
Series
5. Checking the Heating Elements
The most common problems encountered with electric
heaters are:
• Open or bad connections.
• Open, shorted or grounded heating elements.
To troubleshoot the heating elements, disconnect all
leads at the back wall and check each element with a
digital multimeter set to Ohms (W). Correct ratings are
shown in the table in the preceding section. Zero reading on the ohm scale indicates an open or shorted element.
Figure 78
Fan shroud removed
NOTE: Wires going from the mercury contactor (or
solid state relays, as appropriate) to the heating elements are rated at #12 gauge TAGT, 482°F/250°C. DO
NOT, under any circumstances, use a wire of lesser
rating or quality.
NOTE: All lugs and connections are rated at 600°F/
316°C. All heating element connections are doublenutted.
To remove the element:
•
Remove the blower belt.
•
Remove the 12 electrical lead connections to the
heaters at the back wall.
•
Remove the 12 bolts that hold the rear oven panel
to the body. Once removed, DO NOT lay the panel
on either its front or back side. This can damage
the heating elements and blower fan. The panel
should be kept upright as shown in Figure 78.
•
Remove the fan shroud.
•
Remove the screws at both ends of the element
and pull the element straight out. See Figure 79.
•
When replacing the rear oven panel, be sure to use
a high-temperature never-seize lubricant on the 12
bolts that hold the panel in place.
Figure 79
Removing elements
Mounting
screws
141
SECTION 3 - SERVICING COMPONENTS
B. PS310/360-series ovens
2. Part number reference
1. Description of heating system
Part No.
All PS310/360-series electric ovens use an on-off system for heater activation. When the oven demands
heat, the temperature controller activates mercury
contactors that in turn activate the heaters at 100%
power. The contactors open when the temperature rises
to 2 degrees above the set point, and close when the
oven’s temperature falls 2 degrees Fahrenheit below
the set point. Because of residual heat within the oven,
however, the temperature swing after preheating is about
5 degrees Fahrenheit above and below the set point.
IMPORTANT: Because the PS310/360-series
electric oven uses an on-off system for heater
activation, the temperature controller MUST
be set to the on-off operating mode. Refer to
Temperature Controller on Page 30.
Description
27374-0001
Heating element, 208V
27374-0002
Heating element, 240V
27374-0003
Heating element, 380V
28041-0016
Mercury contactor, 3 pole, 30A
27170-0251
Contactor tube replacement kit
27170-0250
Coil replacement kit
28154-0002
Fuse, 30A, class M (early)
28150-0134
Fuse, 40A, class T (current)
27021-0016
Fuse block, 40A (used when upgrading
from 30A to 40A fuse - qty. 3 reqd.)
3. Supply
Each bank of heaters (3 total) uses one mercury
contactor and three fuses. 30A fuses were used
through 1/91. Heat inside the machinery compartment
can de-rate these fuses, causing the fuse to blow prematurely. To correct this situation, 40A fuses were used
2/91 and later.
NOTE: All control wire used on this oven is AWM rated
at 221°F/105°C. DO NOT replace with lower rated wire.
Figure 80
Removing the element bank mounting bolts
Ovens have a 208V, 220-240V, 380V, 416V or 480VAC
electrical supply. The control current of the oven operates at 110V, single phase. If the oven was specified
for a 3 wire system, it was supplied with an optional
control transformer to step the 3 phase current down
for the control circuit. If the oven was specified for a 4
wire system, the 4th (neutral) wire is utilized to split 2
of the 3 incoming 3 phase legs and obtain a separate
110V circuit.
Figure 81
Electrical leads disconnected
142
SECTION 3 - SERVICING COMPONENTS
Ohms (W). Correct ratings are shown in the table in
the preceding section. Zero reading on the ohm scale
indicates an open or shorted element.
4. Heater specifications
•
PS310/360-series electric ovens use 18 heating
elements in 3 banks (6 elements per bank).
•
208V elements are used for ovens with a 208V
supply.
•
240 volt elements are used for ovens with a 220, 230
or 240V supply. 240V elements are also used on
ovens with a 416V or 480V supply (connected in series).
•
380V elements are used for ovens with a 380V
supply.
•
All heaters are connected in Delta.
•
Each element is stainless-clad and has a 4-7/8”/
124mm cold (unheated) end next to the connecting leg.
•
Individual element electrical data
Volts
Watts
Ohms
Connection
208V
220V
230V
240V
380V
416V
480V
1350W
1134W
1239W
1350W
1350W
1013W
1350W
32W
42.7W
42.7W
42.7W
107W
42.7W
42.7W
Parallel
Parallel
Parallel
Parallel
Parallel
Series
Series
It is also possible to check for an open element using
an ampmeter. Any current through the element indicates that the element is not open.
6. Changing Heating Elements
NOTE: Wires going from the mercury contactors to
the heating elements are rated at #12 gauge TAGT,
482°F/250°C. DO NOT, under any circumstances, use
a wire of lesser rating or quality.
NOTE: All lugs and connections are rated at 600°F/
316°C. All heating elements are double-nutted. The
rear of each heating element is held to other elements
by a spacer bracket. The only way the element can be
changed is by removing the entire bank from the oven.
To remove the element bank:
1. Remove the 4 bolts holding the bank of element to
the oven. See Figure 80.
2. Remove the 9 electrical leads going to the element
bank. See Figure 81.
3. Gently work the bank of elements out of the oven.
Be careful not to pinch the wires between the frame
of the oven and the side plate of the heating elements. See Figure 82.
5. Checking the Heating Elements
The most common problems encountered with electric
heaters are:
• Open or bad connections.
• Open, shorted or grounded heating elements.
To troubleshoot the heating elements, disconnect all
leads from ALL of the elements in the bank. Then,
check each element with a digital multimeter set to
4. Remove the bank of elements and place them on
the floor. The entire bank may now be serviced.
5. Remove the element jumper wires and element cover
if individual elements need replacement.
NOTE: The spacer brackets MUST be reinstalled before assembling the element bank back into the oven.
These brackets keep the elements from touching each
other during use. See Figure 82.
Figure 82
Element bank removed - spacer bracket visible
Spacer
brackets
143
SECTION 3 - SERVICING COMPONENTS
C. PS555 ovens
3. Supply
1. Description of heating system
Ovens have a 208V, 220-240V, 380V or 480VAC electrical supply. The control current of the oven operates
at 208/240V.
All PS555 electric ovens use a variable pulse system
for heater activation.
208V and 240V ovens use a 3-wire system (4-wire including the ground connection). The control circuit operates at line voltage.
In response to the millivolt signal from the thermocouple,
the temperature controller sends a 4-20mA signal to a
controller module. This module contains an amplifer
board and two solid state relays. The amplifier board
receives the 4-20mA signal and in turn activates the
relays. The relays then activate the heating elements.
The relays operate on a fixed cycle time. Within each
cycle, the relays activate the heating elements at 100%
for a length of time that is proportional to the signal
from the amplifier board.
380V and 480V ovens use a 4-wire system (5-wire including the ground connection). The 4th (neutral) wire
is utilized to split the incoming 3 phase legs and obtain
a separate control circuit at 208/240V.
4. Heater specifications
When the oven is switched on, heat demand is at its
peak and the elements are activated for 100% of each
cycle. As the oven’s temperature approaches the set
point, the relays reduce the length of time that the heaters are activated wihin each cycle. After the oven is
fully preheated, the heaters are usually activated for
about 30% of each cycle. This system allows the actual oven temperature can remain constant, with NO
temperature swing.
IMPORTANT: The PS555 electric oven uses a
variable pulse system that is designed to emulate the PID gas operating mode. Because of
this, the temperature controller MUST be set
to the PID operating mode.
Temperature controller P/N 46837 (inc. with
Service Kit 47321) includes a dedicated variable pulse mode intended for the PS536 electric oven. This mode is NOT used on the PS555
electric oven. If you are using controller P/N
46837, be sure to set the controller for the PID
operating mode.
Refer to Temperature Controller on Page 30.
Heaters are arranged into four assemblies, each of
which contains three elements. Each pair of assemblies (left and right) share a controller and a 50A circuit
breaker block.
NOTE: All control wire used on this oven is AWM rated
at 221°F/105°C. DO NOT replace with lower rated wire.
2. Part number reference
Part No.
•
PS555 electric ovens use 12 heating elements in 4
assemblies (3 elements per assembly). Elements
CANNOT be removed from the assembly. If one
element is not functioning properly, the entire assembly should be replaced.
•
208V elements are used for ovens with a 208V supply.
•
240 volt elements are used for ovens with a 220V,
230V or 240V supply.
•
380V elements are used for ovens with a 380V supply.
•
480V elements are used for ovens with a 416V or 480V
supply.
•
All heaters are connected in Delta.
•
Heaters are grouped into four assemblies, each of
which contains three elements. Elements CANNOT be removed from the assembly.
•
Each element has a cold (unheated) end next to
the connecting leg. 12”/0.3m leads are connected
to the cold ends for easy connection to the terminal blocks on the back wall of the oven.
•
Individual element electrical data
Volts
Watts
Ohms
Connection
208V
220V
230V
240V
380V
416V
480V
2667W
2241W
2449W
2667W
2667W
2003W
2667W
16.2W
21.6W
21.6W
21.6W
54.1W
86.4W
86.4W
Parallel
Parallel
Parallel
Parallel
Parallel
Parallel
Parallel
5. Checking the Heating Elements
The most common problems encountered with electric
heaters are:
• Open or bad connections.
• Open, shorted or grounded heating elements.
Description
43337
Heating element assembly, 208V
44525
Heating element assembly, 230V
44526
Heating element assembly, 380V
44527
Heating element assembly, 480V
44914
Controller module, 208/230/240V ovens
44568
Controller module, 380/480V ovens
35018
Circuit breaker block, 50A, 3 pole
144
To troubleshoot the heating elements, disconnect all
leads at the terminal blocks on the back wall. Then,
check each element with a digital multimeter set to
Ohms (W). Correct ratings are shown in the table in
the preceding section. Zero reading on the ohm scale
indicates an open or shorted element.
SECTION 3 - SERVICING COMPONENTS
It is also possible to check for an open element using
an ampmeter. Any current through the element indicates that the element is not open.
6. Changing Heating Elements
NOTE: Wires going from the controller assembly
contactor to the heating elements are rated at 392°F/
200°C. DO NOT, under any circumstances, use a wire
of lesser rating or quality.
To remove the element:
•
Remove the blower belt on the affected side of the
oven.
•
Remove the wireway cover.
•
Disconnect the electrical lead connections from the
front of the oven to the remote terminal blocks on
the back wall. Then, disconnect the leads from
the remote terminal blocks to the elements.
•
Remove the 8 hex bolts that hold the rear wall panel
to the body of the oven. Once removed, DO NOT
lay the panel on either its front or back side. This
can damage the heating elements, blower fan and
bearings. The panel should be kept upright.
•
Remove the two hex head screws that hold the
element assembly to the back wall.
•
When replacing the rear oven panel, be sure to use
a high-temperature never-seize lubricant on the 8
hex bolts that hold the panel in place.
Figure 83
PS555 electric oven heating element removal
Remote
terminal blocks
Lock
washer
Hex
bolt
Flat
washer
Hex head
screw
Heating
element
assembly
Wireway
cover
145
Flat
washer
Hex head
screw
SECTION 3 - SERVICING COMPONENTS
Figure 84
D. Mercury Contactor Replacement
Early PS200-series electric ovens and all PS310/360-series electric ovens use mercury contactors to activate the
heating elements. Each pole in the contactor is a separate
mercury-filled tube that is individually replaceable. This
feature ensures that the entire contactor should never have
to be replaced.
Individual part numbers for the mercury contactor components are listed in the Part Number Reference sections on
Pages 140 and 142, respectively.
1. PS200-series mercury contactor replacement
•
Remove the complete contactor from the oven.
Then, remove the terminal clamps from the
contactor tube(s) to be replaced.
•
Locate the Tinnerman clips on the bottom side of
the contactor that hold each individual contact tube
in place.
•
Find the break in the tube bracket located in the
center. Then, using a diagonal cutter, cut the
Tinnerman clip so that it may be removed.
•
Remove the contact tube. If the coil must be replaced, all three contactor tubes must first be removed.
•
To replace the contactor tube(s), slide the thin end
of the tube into the contactor bracket.
Figure 85
Figure 86
146
SECTION 3 - SERVICING COMPONENTS
•
Support the wide end of the tube between two
pieces of wood so that the terminal end will not be
damaged.
•
Place a deep well socket over the new Tinnerman
clip.
•
Gently tap the socket with a hammer to push the
clip down and into place.
Figure 87
Figure 88
Figure 89
NOTE: When replacing the mercury contactor into
the oven, the wider tube ends must be pointing UP.
The tubes must ALWAYS be mounted in a vertical
position.
147
SECTION 3 - SERVICING COMPONENTS
Figure 90
2. PS310/360-series contactor replacement
•
Remove the two Phillips-head screws holding the
cover in place. Then, remove the cover.
•
Remove the six terminal lug screws. This procedure must be followed when replacing the coil or
any one contact tube.
•
The coil and contact tubes will now pull straight
out from the base. The coil or any individual contact tube can now be replaced.
Figure 91
NOTE: When replacing the mercury contactor into
the oven, the wider tube ends must be pointing UP.
The tubes must ALWAYS be mounted in a vertical
position.
•
Replace the cover and attach it with the two Phillipshead screws. Note that the cover and base are
marked to show correct orientation.
148
Figure 92