MODEL 3250
Temp Limit / LWCO Control
with Thermal Targeting™
for Water Boilers
120 VAC Operating Voltage
PATENT NO. 7,891,572
INSTALLATION INSTRUCTIONS
and OPERATING MANUAL
• Saves Fuel – Features Thermal Targeting™ technology and
Thermal Pre-Purge capability
• Universal Design – Replaces common cold-start and triple-action
Aquastats*
• Easy to Install – Industry standard wiring, dial-type settings,
no external sensors necessary
• Operating Indicators – LEDs, Dynamic Display and Test Button provide
continual and on-demand status checks
• Prioritizes Domestic Hot Water – Gives priority to low limit setting or to
calls from indirect water heater
• Reduces Condensation – Holds circulator off until boiler reaches 120°F
•
*Aquastat is a registered trademark of Honeywell International, Inc.
Three Function
Design
Temperature Limit Control
Designed for cold start and tankless
coil boilers.
Low Water Cut-Off
Provides protection against potentially
dangerous low water conditions
when installed with the Hydrolevel
Electro-Well™ (see page 2 for details).
Boiler Reset Control
Utilizes Thermal Targeting™
technology to conserve fuel by
monitoring heating demand and
establishing target boiler temperatures
below the high limit setting (see page 7
for details).
Electrical shock hazard. To prevent electrical shock, death or
equipment damage, disconnect power supply before
WARNING
installing or servicing control. Only qualified personnel may install or service this control in
To prevent serious
CAUTION
burns, boiler
should be thoroughly cooled before installing or
accordance with local codes and ordinances. Read instructions completely before proceeding.
servicing control.
83 Water Street • New Haven, CT 06511 • Phone (203) 776-0473 • FAX (203) 773-1019 • www.hydrolevel.com
1
IMMERSION WELLS
Fuel Smart HydroStat can be installed on an existing immersion well already in the boiler or on a Hydrolevel Electro-Well™
(sold separately). The low water cut-off function is automatically activated when installed on an Electro-Well™.
IMPORTANT: The control will not provide low water cut-off protection when installed on a standard immersion well.
NOTE: Do not use heat-conducting grease.
Fuel Smart HydroStat installed
with Hydrolevel Electro-Well™
Fuel Smart HydroStat installed
with standard immersion well
IMPORTANT: For proper operation of the low water cut-off function, there
must be a minimum of ½" clearance between the copper well tube and any
surface within the boiler.
NOTE: When installed on a standard immersion well, the “LWCO Active”
LED will not illuminate.
See Electro-Well models on page 12.
MOUNTING THE CONTROL
IMPORTANT Make sure that the immersion well or Electro-Well™ is installed in the boiler manufacturer’s designated
temperature limit control tapping.
NOTE: If installing an Electro-Well, pipe sealing compound should be used. Teflon tape is not recommended.
Two mounting positions
are available on the back of the control
(Fig. 1). Select which of the two positions
(2 knockouts) is best for the location of
the control. Remove the knockout.
STEP 1
Place control on the well.
While holding box against well nut,
tighten well clamp screw. (Fig. 2)
STEP 2
Insert sensor ALL THE
WAY into well through the knockout (A
or B) you have chosen. (Fig. 3)
STEP 3
BACK OF
FUEL SMART HYDROSTAT BOX
FIG. 1
FIG. 2
FIG. 3
NOTE: In the case of space restrictions, the Fuel Smart HydroStat control may be mounted in a horizontal orientation without any
loss of function. Hydrolevel recommends vertical mounting, when possible, for proper orientation of LED display.
REMOTE MOUNTING KITS are available separately for mounting the Fuel Smart HydroStat control box in a remote location.
Each kit includes mounting hardware and a remote sensor. See page 12 for kit options.
2
WIRING
shock hazard. To prevent electrical shock, death or equipment damage, disconnect power supply before
WARNING Electrical
installing or servicing this control.
STEP 1 Connect 120 VAC Hot to terminal L1. Connect
120 VAC Neutral to terminal L2. Disconnect means and
overload protection as required (provided by others).
STEP 2 Connect the burner circuit to B1-B2.
(B2 is neutral.)
Select the Diagram that
Matches your System Configuration
on Pages 4, 5 or 6
3
WIRING
shock hazard. To prevent electrical shock, death or equipment damage, disconnect power supply before
WARNING Electrical
installing or servicing this control.
NOTE: For proper operation of the boiler reset function, all heating thermostats must input to T-T or ZC-ZR terminals as indicated below.
Jumping the T-T terminals and wiring the thermostat to the primary will override the economy feature.
STEP 3A: HEATING ONLY – No Indirect Water Heater
CHOOSE OR BELOW
SINGLE CIRCULATOR
MULTIPLE CIRCULATORS
ZONE/
INDIRECT
SWITCH
POSITION
Connect thermostat or end switch from zone relay or multizone panel to T-T. Connect circulator to C2-C1. Move
Zone/Indirect Switch up to Z.
ZONE/
INDIRECT
SWITCH
POSITION
Connect end switch from circulator relay or multi-zone panel to
ZC-ZR. Move Zone/Indirect Switch up to Z.
STEP 3B: HEATING and Indirect Water Heater
IMPORTANT: When installing with an indirect water heater, the Zone/Indirect Switch must be set in the I position. When set in the I position, calls to ZC-ZR will
bypass the Thermal Targeting feature and allow the boiler to fire to the high limit setting to heat the indirect tank. The indirect signal must be separate from all
heating zone signals. If you choose not to separate the indirect signal from the heating zones, the Economy Feature should be turned OFF to ensure that the
boiler supplies adequate temperature to heat the indirect tank (see page 7).
CHOOSE FROM THROUGH BELOW OR ON PAGE 5 OR 6
SINGLE CIRCULATOR
MULTIPLE CIRCULATORS
ZONE/
INDIRECT
SWITCH
POSITION
Connect thermostat or end switch from zone relay or multi-zone
panel to T-T. Connect circulator to C2-C1. Connect end switch
from indirect zone relay to ZC-ZR. Move Zone/Indirect Switch
down to I.
ZONE/
INDIRECT
SWITCH
POSITION
Connect end switch from heating circulator relays or multi-zone
panel to T-T. Connect end switch from indirect circulator relay to
ZC-ZR. Move Zone/Indirect Switch to I.
4
WIRING
shock hazard. To prevent electrical shock, death or equipment damage, disconnect power supply before
WARNING Electrical
installing or servicing this control.
NOTE: For proper operation of the boiler reset function, all heating thermostats must input to T-T or ZC-ZR terminals as indicated below.
Jumping the T-T terminals and wiring the thermostat to the primary will override the economy feature.
STEP 3B: HEATING and Indirect Water Heater – continued
MULTIPLE CIRCULATORS — Typical Zone Panel with Priority Zone
ZONE/
INDIRECT
SWITCH
POSITION
NOTE: The wire from ZR to the hot terminal of the indirect circulator will ensure
that indirect calls will fire to limit and receive priority over heating calls.
SINGLE CIRCULATOR — Multiple Zone Valves including Indirect, No Zone Control Panel
ZONE/
INDIRECT
SWITCH
POSITION
NOTE: When using zone valves for both heat and indirect, the calls must be separated in order to prioritize indirect calls. This can
be accomplished by using a general purpose relay as shown above. However, for ease of installation, a zone control panel is recommended (see wiring diagram 7 on next page).
MORE
5
WIRING
shock hazard. To prevent electrical shock, death or equipment damage, disconnect power supply before
WARNING Electrical
installing or servicing this control.
NOTE: For proper operation of the boiler reset function, all heating thermostats must input to T-T or ZC-ZR terminals as indicated below.
Jumping the T-T terminals and wiring the thermostat to the primary will override the economy feature.
STEP 3B: HEATING and Indirect Water Heater – continued
SINGLE CIRCULATOR — Typical Multiple Zone Valve Panel with Indirect
ZONE/
INDIRECT
SWITCH
POSITION
NOTE – If a Zone Valve Control Panel has no priority zone: To ensure adequate boiler temperature to satisfy the domestic hot water tank, it may be necessary to turn the Economy Feature off.
MULTIPLE CIRCULATORS — Typical Three Zone Switch Relay
ZONE/
INDIRECT
SWITCH
POSITION
NOTE: The wire from ZR to the hot terminal of the indirect circulator will ensure
that indirect calls will fire to limit and receive priority over heating calls.
Tacoʼs SR503 combines ZR amd X2.
6
SETTING THE CONTROL
NOTE: Settings can be checked using the
TEST/SETTINGS Button. See page 8 for details.
Diagnostic LEDs
and Test Button
Dynamic
Display
The high limit is factory set at 190°F. To adjust, turn the HI
TEMP Dial until the desired setting is displayed.
(Setting range: 100°-220°F)
Setting the High Limit
Jumper
Water Temperature
and Real Time
Verification of
Setting Adjustments.
The low limit is designed to maintain temperature in boilers equipped with tankless coils used for domestic hot
water. The low limit is factory set to OFF. Prior to adjusting, remove the jumper (not equipped on all units) .
Then turn the LO TEMP Dial clockwise until the
desired temperature is displayed. For proper operation,
the low temperature limit setting should be at least 10°
below the high limit setting. NOTE: For cold start operation, the low limit must be turned OFF. IMPORTANT: If low
limit temperature cannot be set above 140°F, remove
jumper . (Setting range: OFF or 110°-200°F).
Setting the Low Limit
Low Temperature
Limit Setting
(OFF or 110°-200°F)
Factory OFF
Zone/Indirect
Switch
Indicator Light
(announces heat call)
High Temperature
Limit Setting
(100°-220°F)
Factory 190°F
Economy Dial
(OFF or LO, 1, 2, 3,
4, 5, HI)
Differentials
are automatic
and will vary
based on
control settings
and boiler temperature.
The Economy Feature is factory set for a 1 zone heating system. To adjust, turn the ECONOMY Dial until the number
displayed equals the number of heating zones. Do not
include indirect water heaters in the number of heating
zones. The Economy Feature conserves fuel by reducing
boiler temperature (see “How Thermal Targeting Works”
below). If the heating system is unable to supply needed heat
to the house, the ECONOMY Dial should be turned to a lower
setting (example: In a three zone house, turn the dial to 2 or
1). Conversely, if the boiler provides adequate heat, added
fuel savings can be achieved by selecting a higher setting
(example: 4 or 5). If the heating and indirect water heater
signals were not separated when wiring the control, the
Economy Feature should be turned OFF to ensure the boiler
supplies
SETTING
adequate
Disables economy function. Will allow boiler to fire until
hi-limit temp is reached and re-fire with a 10° subtractive
temperadifferential.
ture to
Provides lowest level of fuel savings. Use this setting only
heat the
if the house does not stay warm at higher settings.
indirect
Recommended setting for single zone systems
tank.
Recommended setting for Two zone systems
Setting the Economy Feature
See WIRING on page 4-6.
Setting the Zone/Indirect Switch
NOTE: Activation of this feature is not
recommended for boilers with tankless coils.
Activating Thermal Pre-Purge (optional)
Fuel Smart HydroStat has a Thermal Pre-Purge feature to
maximize efficiency. When activated, the control will purge
higher boiler temperatures down to 135° at the start of any
thermostat call and supply the latent energy in the boiler to the
heating zone that is calling. During the purge cycle, the display will indicate Pur. If the heat is not sufficient to satisfy the
thermostat, the control will energize the burner. This feature
works with single- and multi-zone heating systems utilizing circulators or zone valves. No change in wiring is needed.
To Activate Thermal Pre-Purge
Push and hold the TEST/SETTINGS button for 20 seconds.
The display will read Pur On. To deactivate the feature, push
and hold the button a second time for
20 seconds. The display will read Pur OFF.
Recommended setting for Three zone systems
Recommended setting for Four zone systems
Recommended setting for Five zone systems
Provides highest level of fuel savings
SYSTEM START-UP
At initial start up, with the Economy Feature active, the control establishes a 145°F target temperature. To test the high limit
shut-off function, the Economy Dial must be turned to OFF. Once tested, restore the Economy setting. If the heating demand is
high, the target will increase over time to satisfy the heat load. NOTE: To reduce the potential for condensing, the control
will allow the boiler to heat to 120°F prior to energizing the circulator.
HOW THERMAL TARGETING WORKS
Thermal Targeting technology analyzes thermostat activity and continually evaluate how much heat the house requires. When it
is very cold outside, the heat demand is high and the Fuel Smart HydroStat will raise the boilerʼs Target temperature to provide
needed heat to the home. When the outside temperature is milder, the heat demand is lower. During these periods, the Fuel
Smart HydroStat will lower the boilerʼs Target temperature – saving fuel – while continuing to provide comfort to the house.
7
LED LEGEND and TEST/SETTINGS BUTTON
TEMP ACTIVE
down. The boiler water will continue to circulate and heat the
house as long as the thermostat call continues. The LED will
stay lit until the boiler temperature drops below the
differential set point at which point the boiler will be allowed
to fire again. See Differential explanation on page 7.
NOTE: This LED illuminates regularly during normal boiler
operation.
Indicates that the Fuel Smart
HydroStat control is powered and that the temperature
function is active.
TEMP HI TEMP
Illuminates when the boiler water
temperature reaches the high limit setting. It will remain lit
until the water temperature falls 10°. The Fuel Smart
HydroStat prevents burner operation while this LED is on.
See Differential explanation on page 7.
TEST/SETTINGS Button
To Test Low Water Cut-Off: Press and hold the Test/
Settings button for 5 seconds. The display will read LCO.
LWCO ACTIVE
Indicates that the low water cut-off
(LWCO) function of the Fuel Smart HydroStat is active. When
the control is installed with a Hydrolevel Electro-Well, this
LED will be on at all times when the control is powered.
IMPORTANT: If the control is installed with a well other than
the Electro-Well, this LED will not illuminate indicating that
the control is not providing low water cut-off functionality.
LWCO TEST
00
The red Low Water light should illuminate and the burner
circuit (B1 and B2) should de-energize. NOTE: The control
must be installed with a Hydrolevel Electro-Well for low water
cut-off functionality (see page 2 for more details).
LWCO LOW WATER Illuminates if the boiler is in a
low water condition. The Fuel Smart HydroStat will prevent
burner operation during this condition. IMPORTANT: The
system must be checked by a qualified heating professional
prior to resuming operation.
WARNING: DO NOT ADD WATER UNTIL THE BOILER
HAS FULLY COOLED.
To View Current Settings: Press and release the
Test/Settings Button in short intervals to sequentially display
the following settings:
HIGH LIMIT SETTING
LOW LIMIT SETTING
ECONOMY ACTIVE
Indicates that the Thermal
Targeting function is active and the Fuel Smart HydroStat will
reduce boiler temperature to conserve fuel. The Economy
feature is activated using the ECONOMY dial. (See “How
Thermal Targeting Works” on page 7 for more information).
ECONOMY SETTING
00
00
000
CURRENT TARGET TEMPERATURE
ECONOMY TARGET
When the Economy feature is
active, the Fuel Smart HydroStat continually sets target
temperatures below the high limit setting to maximize fuel
efficiency. When the boiler water reaches the target
temperature, the LED illuminates and the burner will shut
PRE-PURGE SETTING
000
The display will return to boiler temperature (default) if
Test/Settings Button in not pressed for 5 seconds.
8
TROUBLESHOOTING
Burner Will Not Fire
Burner Will Not Shut Down
Temperature Display Exceeds
High Limit Setting
No or Insufficient
Domestic Hot Water
Boiler Will Not Maintain
Low Limit Temperature
House Will Not Get
or Stay Warm
Circulator Contacts
C1 and C2 Not Energized
on Call for Heat
See Flow Chart 1, page 10
See Flow Chart 2, page 11
Under normal operation, boiler temperature will continue to rise after the control shuts off
the burner. This condition, known as “thermal stacking”, results from hot boiler surfaces
continuing to release heat into the boiler water.
For boilers equipped with a tankless coil, make sure the low limit setting on the HydroStat
is set properly. NOTE: If the low limit setting is dialed fully counter clockwise, it will shut
off the low temperature maintenance feature and will function as a cold start control. If
installed with an indirect water heater, check that the Zone/Indirect Switch is set in the
Indirect (I) position. Verify that the end switch in the relay box controlling the indirect water
heater is connected to the ZC-ZR terminals. This will ensure that the domestic water calls
are prioritized. (see “Heating and Indirect Water Heater” on page 4-6).
Check for overlapping high temperature setting. If the high limit setting is set below the
low limit setting, the control will default to the high limit setting and the corresponding
high limit differential setting.
1. Check for air-bound radiators. 2. Check thermostat settings including heat anticipator
settings (common on non-digital thermostats). 3. Check the Economy setting. The
Economy feature, much like outdoor reset controls, lowers average boiler temperature
and can slow or, in some cases, prevent the house from coming up to temperature.
Move to a lower setting (see “Setting the Economy Feature” on page 7).
Check to see that boiler water is at or above 120°F. On a call for heat, the control will not
permit the circulator to operate if the boiler water temperature is below 120°F.
9
Troubleshooting Flow Chart 1 – Burner Will Not Fire
Does the
Display Read
YES
The Control is
Purging Latent
Heat from the
Boiler.
NO
The Control is
Not Powered.
?
The Thermal Pre-Purge feature holds off the burner until the
circulator has purged the boiler temperature down to 135°F.
NO
Is the
Green LED
(TEMP ACTIVE)
On?
The Temp Active LED will be on at all times when the control is
powered.
Check for 120 VAC on terminals L1 and L2.
YES
CAUTION – ALWAYS ALLOW A BOILER TO COOL BEFORE ADDING WATER
The burner will not fire until the low water condition is satisfied.
Is the
Red LED
(LOW WATER)
On?
YES
The Control is
Sensing
Low Water.
Check that the sensor is inserted correctly into well.
Note : The use of heat-conductive grease may interfere with the
contact between the spring clip and the copper well tube.
Check that the control is tightly clamped to the well.
NO
Is the
Yellow LED
(HI TEMP)
On?
Check that the system is filled with water.
YES
The Control is
Sensing High
Temperature.
YES
The Boiler has
Reached the
Target
Temperature.
The burner will not fire until the boiler water has dropped to the
high limit differential set-point (10° below high limit setting).
Check that the high temperature setting is correct.
NO
Is the
Yellow LED
(TARGET)
On?
When the ECONOMY function is active, the control monitors heating
demand and establishes Target boiler temperatures below the high
limit setting to conserve fuel (see “How Thermal Targeting Works”
on page 7). The burner will not fire until the boiler temperature
drops to the automatically calculated Target Temp Differential.
NO
Is the
Thermostat
(T-T) Calling
for Heat?
NO
YES
Is There
120 VAC
Between B1
and B2?
Is the
External Zone
(ZC-ZR) Calling
for Heat?
NO
Is the
Low Limit Dial
Set to OFF?
YES
YES
The Control
is Operating
Properly.
NO
HydroStat is supplying 120 VAC to the burner circuit.
Recheck wiring and operation of burner and other limit controls.
NO
Replace
Control
YES
When the low temperature
setting is set to OFF, the
HydroStat will act as a cold
start control. The burner
will not fire unless there is
a call from the thermostat
(T-T) or an external zone
(ZC-ZR).
Set thermostat to call
for heat. Burner should
fire.
If the boiler has a tankless coil, set the Low
Temperature Limit to
maintain temperature.
If both the red and yellow LEDs are off and
there is a call to fire the burner, there will be
120 VAC on terminals B1 and B2.
If 120 VAC is not present, the control should
be replaced.
10
Troubleshooting Flow Chart 2 – Burner Will Not Shut Down
Is the
Red LED
(LOW WATER)
On?
YES
The Control is
Sensing
Low Water.
WARNING!
TURN OFF POWER TO BURNER IMMEDIATELY!
NO
Is either
Yellow LED
On?
CAUTION – ALWAYS ALLOW A BOILER TO FULLY COOL
BEFORE ADDING WATER.
YES
The Control has
Reached Target
or High Limit
Temperature.
YES
The Control is
Operating
Normally.
Recheck wiring. Make sure that burner is wired to
B1. Burner should never fire when red or yellow
LED is lit.
NO
Is the
Thermostat
(T-T) Calling
for Heat?
NO
Is the
External Zone
(ZC-ZR) Calling
for Heat?
The burner will continue to fire when there is a call
from the thermostat or external zone.
YES
The Control is
Operating
Normally.
NO
Check temperature display. When the Low Limit is
set, the HydroStat will fire the burner until the
temperature reaches the Low Limit Setting.
NO
Is the
Low Limit Dial
Set to OFF?
YES
Is there
120 VAC between
B1 and B2?
NO
When there is no call to fire the burner, the voltage
should be 0 volts between B1 and B2.
Recheck
Wiring.
Make sure the burner is wired to B1.
YES
Replace
Control.
If there is no call for heat (from T-T, ZC-ZR or Low
Limit), there should be 0 VAC between B1-B2.
If there is voltage between B1-B2, the control
should be replaced.
11
MAINTENANCE
Remove the Electro-Well from the heating system every five years and clean any scale or sediment deposits from all parts that are
exposed to the boiler water. After cleaning, reinstall the well using pipe sealing compound. Teflon tape is not recommended.
REMOTE MOUNTING KITS
Part No.
48-101
48-102
Description
Part No.
48-103
48-104
48-121
HydroStat Remote Mount Kit with 24" sensor
HydroStat Remote Mount Kit with 48" sensor
ELECTRO-WELLS
Description
HydroStat Remote Mount Kit with 10' sensor
HydroStat Remote Mount Kit with 20' sensor
HydroStat Pipe Mounting Kit with 48" sensor
DIMENSIONS
SPECIFICATIONS
Input voltage
Burner contacts
Circulator contacts
Operating range – low limit
Operating range – high limit
FUEL SMART HYDROSTAT MODEL 3250
120 VAC, 60 HZ
7.4 FLA, 44.4 LRA@120 VAC
5.8 FLA, 34.8 LRA@120 VAC
Off or 110°F - 200°F (43°C - 93°C)
100°F - 220°F (38°C - 104°C)
LIMITED MANUFACTURERʼS WARRANTY
We warrant products manufactured by Hydrolevel Company to be free from defects in
material and workmanship for a period of two years from the date of manufacture or
one year from the date of installation, whichever occurs first. In the event of any claim
under this warranty or otherwise with respect to our products which is made within
such period, we will, at our option, repair or replace such products or refund the purchase price paid to us by you for such products. In no event shall Hydrolevel Company
be liable for any other loss or damage, whether direct, indirect, incidental or consequential. This warranty is your EXCLUSIVE remedy and shall be IN PLACE OF any other
warranty or guarantee, express or implied, including, without limitation, any warranty
of MERCHANTABILITY or fitness for a particular purpose. This warranty may not be
assigned or transferred and any unauthorized transfer or assignment thereof shall be
void and of no force or effect.
83 Water Street • New Haven, CT 06511 • Phone (203) 776-0473 • FAX (203) 773-1019 • www.hydrolevel.com
12
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