PACKAGED AIR COOLED CONDENSING UNIT TYPE ALP-067A THRU 159A INSTALLATION AND MAINTENANCE DATA
BULLETIN NO. IM 173
PACKAGED AIR COOLED CONDENSING UNIT
TYPE ALP-067A THRU 159A
G R O U P
M c Q U A Y - P E R F E X Inc. 13600 Industrial Park Blvd., P.O. Box 1551, Minneapolis, Mn. 55440 @)
Installation and maintenance are to be performed only by qualified personnel who are familiar with local codes and regulations, and experienced with this type of equipment.
CAUTION: Sharp edges and coil surfaces are a potential injury hazard. Avoid contact.
LOW POWER CONSUMING
AIR COOLED CONDENSER
- 089 A D
NOMINAL CAPACITY (TONS)
When the equipment is received, all items should be carefully checked against the bill of lading to insure a complete shipment.
All units should be carefully inspected for damage upon arrival.
All shipping damage should be reported to the carrier and a claim should be filed.
The unit serial plate should be checked before unloading the unit to be sure that it agrees with the power supply available.
Care should be taken to avoid rough handling or shock due to dropping the unit. Do not push or pull the unit from anything other than the base, and block the pushing vehicle away from the unit to prevent damage to the sheet metal cabinet. (See Figure 1.)
SUGGESTED PUSHING ARRANGEMENT
GOOD PUSHING ARRANGEMENT
CABINET DAMAGE UNLIKELY
POOR PUSHING ARRANGEMENT
CABINET DAMAGE LIKELY page 4
Never allow any part of the unit to fall during unloading or moving as this may result in serious damage.
To lift the unit, 2+" diameter lifting holes are provided in the base of the unit. Spreader bars and cables should be arranged to prevent damage to the condenser coils or unit cabinet. (See Figure 2.)
SUGGESTED LIFTING ARRANGEMENT
SPREADER BAR REQD.
O T E
ALP UNIT SIZE UNIT WEIGHT (Ibs)
0 8 9 A 4963
ALP UNIT SIZE
UNIT WEIGHT (Ibs)
Due to the vertical condenser design, it is recommended that certain precautions be taken before installation to orient the unit so that prevailing winds blow parallel to the unit length thus minimizing effects on condensing pressure. If it is not practical to orient the unit in this manner, a wind deflecting fence should be considered.
It is also necessary to provide adequate clearance on all sides of the unit for service access and satisfactory performance.
60 in. (1 fan diameter) should be allowed on each side of the unit for condenser air inlet and compressor removal on units 067 & 078.
If parallel units are installed side by side, 120 in. should be allowed between units. This will prevent excessive condensing temperatures and enhance system performance and operating economy.
Clearance for service access should be at least 78 in. at the control center end for compressor removal on units 089 through 159 and 42 in.
on units 067 and 078. Allow 36 in.
clearance at the end opposite the control center for ease of access to bearings and drives.
These clearances are illustrated in Figure 3.
FIGURE 3 CLEARANCE AROUND UNIT
60” MINIMUM CLEARANCE (2)
M I N I M U
M CLEARANCE (2)
(I) Minimum vertical clearance above unit should be 10 feet.
(2) Clearance to condenser coil must be increased if more than one side is obstructed or between adjacent units.
Consult your McQUAY sales representative.
Each end of the unit must be accessible after installation for periodic service work. Compressors and manual liquid line shutoff valves are accessible from the control center end of the unit through removable access panels on unit sizes 089 through 159 and hinged side access doors on unit sizes 067 and 078. All operational, safety, and starting controls are located in the unit control center. They are protected by a keylocked, weatherproof enclosure which contains internal "dead front" doors for protection of service personnel from high voltage starting controls while servicing low voltage operational controls. All resettable or adjustable controls are located just below the main control center. There is one resettable control enclosure on each side of the unit and each enclosure contains controls for compressors on that side of the unit. Capped connections for field service gauges are also located inside these enclosures.
In addition, each of these enclosures are removable to improve access to compressors for field replacement.
The condenser fans, motors, and drives are accessible through a walkin, keylocked access door. The access door is located at the end of the unit opposite the control center.
An internal fan guard is located below the condenser fans and drives on units 089 through 159. This guard must be removed to service the fan drives but MUST always be reinstalled when service work is complete.
On unit sizes 067 and 078, an interlock switch kills power to condenser fans whenever the door is opened for service work on fans or drives.
CAUTION: Disconnect all power to the unit while servicing condenser fan drives.
Vibration isolators are recommended for all roof mounted installations or wherever vibration transmission is a consideration.
2 lists spring isolators for all ALP unit sizes.
Figure 4 shows isolator locations in relation to the unit control center.
Figure 5 gives dimensions that are required to secure each M c Q u a y isolator selection to the mounting surface.
Table 3 shows the isolator loads at each location shown in Figure 4 and the maximum loads for each McQuay selection.
TABLE 2 VIBRATION ISOLATORS
TABLE 3 IS0 LATOR LOADS
McQuay type ALP condensing units are adaptable to either chilled water or air handling air conditioning applications. The only restriction on applications is that the evaporator be selected for a system using refrigerant 22.
Evaporator Above Condensing Unit
Figure 6 shows an installation where the evaporator is installed above the condensing unit. It is shown for an air handling installation but all components shown are recommended for chilled water installations except that a refrigerant distributor is not usually required for shell-and-tube evaporators.
FIGURE 6 EVAPORATOR ABOVE CONDENSING UNIT
Legend a Filter-drier b Solenoid valve
Thermal expansion valve e Suction line, pitched toward compressor f Liquid line
1. Piping shown is for one circuit only, second circuit is similar.
2. All piping & piping components are by others.
Evaporator Below Condensing Unit
Figure 7 shows an installation where the evaporator is installed below the condensing unit. It is shown for an air handling installation but all components shown are recommended for chilled water installations except that a refrigerant distributor is not usually required for shell-and-tube evaporators.
Mote that a double suction riser is shown for this arrangement.
Risers "A + B" are sized so that their combined cross-sectional internal area will allow full load unit operation without excessive pressure drop (see notes, Table 4). Riser "B" is sized to provide adequate suction gas velocity for proper oil return at minimum load conditions. This riser becomes effective only when the trap shown in riser "A" fills itself with oil.
It should be emphasized that
the trap shown in riser "A" should be designed to contain a minimum internal volume to keep the total system oil requirements at a minimum. Table 4 gives recommended line sizes for both single and double suction lines and for liquid lines.
Figure 9 shows typical field wiring that is required for unit installation. Items that require field wiring are: liquid line solenoids
(SVl & SV2), optional hot gas bypass solenoid (SV5) and the cooling thermostat as well as the unit power supplies.
TYPICAL FIELD WIRING
DISCONNECT UNIT MAIN
B Y O T H E R S - - \ , , < T E R M I N A L B L O C K
3pH ---_H _ _ _
CONI, llNlT COMPRESSORS c A N D F A N M O T O R S
SuppLy _ _ __I’_ - -
POWER FOR CONTROLS
LEGEND i g_ ~~~SLT~OM~~~,~~NNECTION
I ‘,‘-- DISCONNECT BY OTHERS O P T I O N A L FdSEU
I irJH_WHlTt WlhlNG fNEUT1.
- F L O W S W I T C H
REFRIGERANT CIRCUIT I
SAFETY AND OPERATING
SVl,2-LIOUID ’ INE
SVS-HOT GAS BY PASS
R3,4-COMP. 3 8 4 S T A R T
R5,6,7,E -SAFETY RELAYS
CING TIME DELAYS
Rx-EVAP. FAN INTERLOCK
SV’S WITHOUT LOAD
DOWN DURING OFF
REFRIGERANT CIRCUIT 2
SAFETY AND OPERATING
UNIT CONDENSER FANS
P U M P S T A R T E R
CC. W. S Y S T E M S 1
R9 RIO NOTE; CIRCUIT SHOWN ASSUMES CONTINUOUS
P U M P OPERATIIN~FOR I N T E R M I T T E N T
I I 1 PUMP OPERATION CONSULT McOUAY a0 __:
T I I I
Since it is impossible for McQuay to anticipate the type of installation that an ALP condensing unit may be used on, we do not factory install a thermostat. We do, however, provide numbered terminals inside the unit control center to which a thermostat may be connected.
These terminals are shown and labeled "Terminals For Thermostat" on the electrical schematics.
On a two circuit unit it is important to connect the thermostat so that as successive stages of cooling are called for, the compressors in the unit will be started to alternately increase the condenser load from refrigerant circuit 1 to circuit 2. This is illustrated in Table 9. Figure 10 shows how to install 2 independent four stage thermostats for controlling an 8 stage unit and Figure 11 shows typical field wiring for an 8 stage thermostat.
Flow Switch for Chilled Water Applications
A WATER FLOW SWITCH MUST BE MOUNTED in either the entering or leaving water line to insure that there will be adequate water flow and cooling load to the evaporator before the unit can start.
This will safeguard against slugging the compressors on start up.
It also serves to shut down the unit in the event that water flow is interrupted to guard against evaporator freeze up.
A flow switch is available from McQuay under ordering number 860-
175033x-00. It is a "paddle" size from 1" to 6" nominal.
type switch and adaptable to any pipe
Certain minimum flow rates are required to close the switch and are listed in Table 11. Installation should be as shown in Figure 13.
TABLE 11 FIGURE 13
FLOW SWITCH MINIMUM FLOW RATES
NOMINAL MINIMUM REQUIRED
PIPE SIZE FLOW TO ACTIVATE
(INCHES) SWITCH (GPM)
1 l/4 9.80
1 l/2 12.70
2 l/2 24.30
MARKED ON SWITCH
1.00 NPT FLOW SWITCH
AFTER SWiTCH BEFORE SWITCH
Electrical connections in the unit control center should be made at terminals 11 and 12. The normally open contacts of the flow switch should be wired between these two terminals. There is also a set of normally closed contacts on the switch that could be used for an indicator light or an alarm to indicate when a "no flow" condition exists.
Evaporator Fan Interlock for Air Handler Coil Installations
It is important to interlock the air handler evaporator fan with the condensing unit control center to insure that there will be a cooling load on the evaporator before the unit can start, to prevent compressor slugging. A pair of terminals for each refrigerant circuit is available in the unit control center for this purpose.
These terminal numbers are shown in Figure 12.
UNIT LAYOUT AND PRINCIPLES OF OPERATION
All electrical controls are enclosed in a weatherproof control center with keylocked, hinged access doors. The control center is composed of three separate enclosures. The upper enclosure is the largest and contains all of the 208,
230, or 460 volt compressor and fan motor starting controls. Also included in this enclosure but partitioned separately are the exposed terminal type - 115 volt operational controls. A "dead front" cover over the high voltage section protects service personnel from high voltage starting controls while servicing low voltage operational controls.
Below the upper enclosure are two smaller, separate enclosures that contain 115 volt adjustable or resettable controls. There is one of these enclosures on each side of the unit, and each contains controls for the compressors on that side.
Power supply conduits are intended to come into the bottom of the upper enclosure and between the two lower enclosures. It is recommended that the unit disconnect switch be mounted away from the unit but Figure 14 recommends a unit mounting arrangement if the disconnect must be unit mounted.
FIGURE 14 POWER CONDUIT ENTRY
Power into unit
ALP-089A THRU 159A ALP - 067A THR U 078A
Sequence of Operation
The following sequence of operation is typical for ALP Seasoncon air cooled condensing unit operation. It is written for a 4 compressor unit, but where components that apply to the fourth compressor are referred to, the equivalent components for the third and second compressors are indicated in parentheses.
With the control circuit power on, control stop switch Sl closed, and manual pumpdown switches PSl and PS2 closed ("Auto." position),
115 volt power is applied through control circuit fuse Fl to the compressor crankcase heaters HTRl through HTR4, (HTR3, HTR2), and also to the contacts of low pressure switches LPl and LP2.
When the remote time clock, ambient thermostat, manual shutdown switch and/or evaporator fan interlocks energize the thermostatic circuit, and provided that high pressure controls HP1 and 2 and compressor motor protectors MPl through PIP4 (MP3, MP2) do not sense an alarm condition, safety relays R5 through R8 (R7, R6) are energized closed applying power to the temperature control thermostat. At this point the unit will operate automatically in response to the thermostat.
On a call for cooling, the temperature control thermostat TCl energizes liquid line solenoid valve SVl, opening the valve and allowing refrigerant to flow into the evaporator. As refrigerant pressure builds up, low pressure control LPl closes, energizing low pressure relay R9 which closes to energize compressor contactor Ml, starting compressor number 1. Closing relay R9 contacts also energizes condenser fan relay R17. Closing its contacts and providing power to condenser fan motor contactors Mll, 12 & 13 on 3 & 4 compressor units, or Mll, & 12 on 2 compressor units.
If additional stages of cooling are required, temperature control thermostat TCl energizes liquid line solenoid valve SV2 after time delay relay TDll has sequenced closed, to initiate the same starting sequence in refrigerant circuit number 2.
On 3 and 4 compressor units, if additional cooling is still required, the third and fourth stages of temperature control thermostat TCl energize the third and fourth compressors after time delay relays
TD12 and TD13 have sequenced closed.
As the temperature control thermostat is satisfied, it opens its contacts, de-energizing liquid line solenoid valve SVl, causing the valve to close. When the compressor has pumped most of the refrigerant from the evaporator to the condenser, the low pressure control
LPl opens, shutting down the compressor and condenser fan motors.
Should a closed solenoid valve allow refrigerant to leak to the low side of the refrigerant circuit during unit "off" time, the buildup in pressure will cause the low pressure control to close, energizing the low pressure relay and starting the compressor for pumpdown.
NOTE: Models ALP-067AS and 078AS have single refrigerant circuits but dual pumpdown switches (PSl & PS2). To manually pump these units down, it is recommended that both pumpdown switches be moved to the "man.pumpdown" position simultaneously.
START-UP AND SHUT-DOWN
With all electric disconnects open, check all screw or lug type electrical connections to be sure they are tight for good electrical contact.
Although all factory connections are tight besome loosening may have resulted from shipping vibration.
a) On chilled water installations, check to see that all water piping is properly connected.
b) Open all water flow valves and start the chilled water pump.
Check all piping for leaks and vent the air from the evaporator and system piping to obtain clean, non-corrosive water in the evaporator circuit.
Check the compressor oil level. Prior to start-up, the oil level should cover at least l/2 of the oil sight glass.
compressor shipping blocks that are attached to the compressor rails and the base of the unit. The ALP 067 and 078 do not have shipping blocks.
Check the voltage of the unit power supply and see that it is within the + 10% tolerance that is allowed. Phase voltage unbalance must be within t
Check the unit power supply wiring for adequte ampacity and a minimum insulation temperature rating of 75C.
Verify that all mechanical and electrical inspections have been completed per local codes.
See that all auxiliary control equipment is operative and that an adequate cooling load is available for initial start up.
1. Open the compressor suction and discharge shutoff valves until back seated.
Always replace valve seal caps.
Open the manual liquid line shutoff valve at the outlet of the
Check to see that pumpdown switches (PSl &
are in the Isman.
pumpdown" position and the control stop switch (Sl) is in the
4. Adjust the dial on the temperature controller to the desired chilled water or leaving air temperature.
Throw the main power and control circuit disconnects to the "on" position.
CAUTION: Most relays and terminals in the unit control center are hot with Sl and the control circuit disconnect on.
Allow the crankcase heaters to operate for at least 8 hours prior to start-up.
Start the auxiliary equipment for the installation.
8. Start the system by moving pumpdown switches (PSl & PS2) to the
9. After system performance has stabilized, it is necessary that the
"Compressorized Equipment Warranty Form" (form no. 206036A) be completed to obtain full warranty benefits. This form is shipped with the unit and after completion should be returned to McQuay's
Service Department through your sales representative.
Move pumpdown switches (PSl & PS2) to the "man. pumpdown" position.
After the compressors have pumped down, turn off the chilled water pump or evaporator fan. It is especially important on chilled water installations that the compressors pump down before the water flow to the evaporator is interrupted to avoid freeze up.
Start-Up After Temporary Shut-Down
1. Start the chilled water pump or evaporator fan.
2. With control stop switch (Sl) in the "on" position, move pumpdown
switches (PSl & PS2) to the '"auto. pumpdown" position.
Observe the unit operation for a short time to be sure that the compressors do not cut out on low oil pressure.
Close the manual liquid line shutoff valves.
2. After the compressors have pumped down, turn off the chilled
water pump or evaporator fan.
Turn off all power to the unit and to the auxiliary equipment.
Move the control stop switch (Sl) to the "off" position.
5. Close the compressor suction and discharge valves.
6. Tag all opened disconnect switches to warn against start up before opening the compressor suction and discharge valves.
Start-Up After Extended Shut-Down
Inspect all auxiliary equipment (pumps, fans, etc.) to see that each device is in satisfactory operating condition.
Remove all debris that has collected on the surface of the condenser coils.
Open the compressor suction and discharge valves.
Open the manual liquid line shutoff valves.
Check to see that pumpdown switches (PSl 6; PS2) are in the "man.
Turn on the electric power to the unit and other parts of the system.
Allow the crankcase heaters to operate for at least 8 hours prior to start-up.
On chilled water installations, start the chilled water pump and purge the water piping as well as the evaporator.
Check to see that the control stop switch (Sl) is in the "on" position.
CAUTION: Most relays and terminals in the unit control center are hot with Sl and the control circuit disconnect on.
10. Start the unit by moving pumpdown switches (PSl & PS2) to the
11. After running the unit for a short time, check the oil level in each compressor crankcase and check for flashing in the refrigerant sight glass.
On initial start up and periodically during operation it will be necessary to perform certain routine service checks. Among these are checking the compressor oil level and taking condensing, suction and oil pressure readings. During operation, the oil level should be visible in the oil sight glass with the compressor running. On units ordered with gauges, condensing,suction and oil pressures can be read from the unit control center. The gauges are factory installed with a manual shutoff valve on each gauge line. The valves should be closed at all times except when gauge readings are being taken. On units ordered without gauges, the gauge shutoff valves come factory installed inside the unit control center for convenient connection of service gauges form outside the unit.
Fan Shaft Bearings
The fan shaft bearings do not require lubrication at the time the unit is put into service. The fan shaft bearings should be greased once a year using STANDARD OIL COMPANY AMCO Multi-Purpose Lithium
Grease. DO NOT OVERLUBRICATE.
Fan Motor Bearings
All fan motors are ball bearing, pre-lubricated and do not require the addition of grease at the time of installation. Periodically, the ball bearings should be cleaned and the grease renewed, to gain the ultimate in service from the motor bearings.
Extreme care must be exercised to prevent foreign matter from entering the ball bearings. It is also important to avoid overgreasing.
Only a high grade clean mineral grease having the following characteristics should be used. Consistency: A little stiffer than that of Vaseline, maintained over the operating temperature range; melting point preferably over 150C (302OF); freedom from separation of oil and soap under operating and storage conditions and freedom from abrasive matter, acid, alkali and moisture.
Specific greasing instructions are to be found on the label attached to the unit and should be generally followed.
CAUTION: ELECTRIC SHOCK HAZARD,
TURN OFF ALL POWER BEFORE CONTINU-
ING WITH FOLLOWING SERVICE.
All power electrical terminals should be retightened every 6 months, as they tend to loosen in service due to normal heating and cooling at the wire.
Compressor Oil Level
Because of the large refrigerant charge required in an air cooled condensing unit it is usually necessary to put additional oil into the system. The oil level should be watched carefully upon initial start up and for sometime thereafter.
At the present time, Suniso #3GS oil is the only oil approved by
Copeland for use in these compressors. The oil level should be maintained at about the midpoint of the sight glass on the compressor body.
Condensers are air cooled and constructed with 3/8 0-D. copper tubes bonded in a staggered pattern into rippled aluminum fins. No maintenance is ordinarily required except the occasional removal of dirt and debris from the outside surface of the fins. Care should be taken not to damage the fins during cleaning. Periodic use of the purge valve on the condenser will prevent the buildup of non-condensables.
Refrigerant Sight Glass
The refrigerant sight glasses should be observed periodically. (A monthly observation should be adequate.) A clear glass of liquid indicates that there is adequate refrigerant charge in the system to insure proper feed through the expansion valve. Bubbling refrigerant in the sight glass indicates that the system is short of refrigerant charge. On sight glasses ordered from XcQuay as part of the
"Liquid Line Accessory Kits" listed on page 12, an element inside the sight glass indicates what moisture condition corresponds to a given element color. If the sight glass does not indicate a dry condition after a few hours of operation, the unit should be pumped down and the cores in the filter-driers changed.
SERVICE ON THIS EQUIPMENT TO BE PERFORMED BY QUALIFIED REFRIGERATION SERVICE PER-
SONNEL. CAUSES FOR REPEATED TRIPPING OF SAFETY CONTROLS MUST BE INVESTIGATED AND
To change the filter drier core(s)
pump the unit down by moving pumpdown switches (PSl & PS2) to the "man. pumpdown" position. Turn off all power to the unit and install jumpers from terminals 21 to
24 and 41 to 44. Turn power to the unit back on and re-start the unit by moving pumpdown switches (PSl & PS2) to the "auto. pumpdown" position. Close the manual liquid line shutoff valve(s) and when evaporator pressure reaches 0 PSIG, move the control stop switch
(Sl) to the "off" position.
This will close the liquid line solenoid valve(s) and isolate the short section of refrigerant piping containing the filter-drier(s). Remove the cover plate from the filter-drier shell and replace the core(s).
After core replacement, replace the cover plate. A leak check around the flange of the filter-drier shell is recommended after the cores have been changed.
Liquid Line Solenoid Valve
The liquid line solenoid valves, which are responsible for automatic pumpdown during normal unit operation, do not normally require any maintenance.
They may, however, require replacement of the solenoid coil or of the entire valve assembly.
The solenoid coil may be removed from the valve body without opening the refrigerant piping by moving pumpdown switches (PSl & PS2) to the 1'man. pumpdown" position. The coil can then be removed from the valve body by simply removing a nut or snap ring located at the top of the coil. The coil can then be slipped off its mounting stud for replacement. Be sure to replace the coil on its mounting stud before returning pumpdown switches (PSl & PS2) to the "auto. pumpdown" position.
To replace the entire solenoid valve, the unit must be pumped down by use of the manual liquid line shutoff valve.
Thermostatic Expansion Valve
The expansion valve is responsible for allowing the proper amount of refrigerant to enter the evaporator regardless of cooling load. It does this by maintaining a constant superheat.
(Superheat is the difference between refrigerant temperature as it leaves the evaporator and the saturation temperature corresponding to the evaporator pressure.) Typically,
superheat should run in the range of 10F to
On valves purchased through McQuay, the superheat setting can be adjusted by removing a cap at the bottom of the valve to expose the adjustment screw. Turn the screw clockwise (when viewed from the adjustment screw end) to increase the superheat setting and counterclockwise to reduce superheat. Allow time for system rebalance after each superheat adjustment.
I N L E T
O U T L E T
Trouble Shooting Chart
PROBLEM POSSIBLE CAUSES POSSIBLE CORRECTIVE STEPS
Compressor will not run
1. Main switch open. 1. Close switch.
2. Fuse blown. Circuit breakers open. 2. Check electrical circuits and motor winding for shorts or grounds. Investigate for possible overloading. Replace fuse or reset breakers after fault is corrected.
3. Thermal overloads tripped. 3. Overloads are auto. reset. Check unit closely when unit comes back on line.
4. Defective contactor or coil. 4. Repair or replace.
5. System shut down by safety devices. 5. Determine type and cause of shutdown and correct it before resetting safety switch.
6. No cooling required. 6. None. Wait until unit calls for cooling.
7. Liquid line solenoid will not open. 7. Repair or replace coil.
8. Motor electrical trouble 8. Check motor for opens, short circuit, or burn out.
9. Loose wiring. 9. Check all wire junctions, Tighten all terminal screws.
I. Flooding of refrrgerant Into crankcase. 1. Check setting of expansion valve.
Compressor noisy 2. Improper piping support on suction or 2. Relocate, add or remove hangers.
or vibrating liquid line.
3. Worn compressor 3. Replace.
1. Non-condensibles in system.
I. Purge the non-condensibles.
2. System overcharged with refrigerant. 2. Remove excess.
3. Discharge shut off valve partially closed. 3. Open valve.
4. Seasontrol out of adjustment 4. Adjust Seasontrot valves.
5. Fan not running. 5. Check belts and electrical crrcuit.
I. Faulty condenser temperature regulation.
I. Check condenser control operation.
2. Suction shut-off valve partially closed. 2. Open valve.
Low Discharge 3. insufficient refrrgerant in system. 3. Check for leaks. Repair and add charge.
Pressure 4. Low suction pressure. 4. See Corrective Steps for low suction pressure below.
5. Compressor operating unloaded. 5. See Corrective Steps for failure of compressor to load up below.
1. Excessive load.
1. Reduce load or add additional equipment.
High Suction 2. Expansron valve overfeedrng. 2. Check remote bulb. Regulate superheat.
Pressure 3. Compressor unloaders open. 3. See Corrective Steps below for failure of compressor
1. Lack of refrigerant.
to load up.
1. Check for leaks. Repair and add charge.
2. Evaporator dirty. Plugged acr filters. 2. Clean chemrcally.
3. Clogged liqurd lrne filterdrier. 3. Replace cartridge(s).
4. Clogged suction line or compressor suction. 4. Clean strarners.
5. Expansion valve malfunctioning. 5. Check and reset for proper superheat.
6. Condensing temperature too low. 6. Check means for regulating condensing temperature.
7. Compressor will not unload. 7. See Correctrve Steps for failure of compressor to unload.
Compressor will not 1. Defective capacrty control.
unload or load up. 2. Pressurestat not set for application. 2. Reset pressurestat setting to fit applicatron.
Little or no oil pressure
1. Clogged suction oil strainer. 1. Clean.
2. Excessive liquid rn crankcase. 2. Check crankcase heater. Reset expansion valve for higher superheat. Check liquid line solenoid valve operation.
3. Oil pressure gauge defective. 3. Repair or replace. Keep valve closed except when taking readings.
4. Low oil pressure safety switch defective. 4. Replace.
5. Worn 011 pump. 5. Replace.
6. Oil pump reversing gear stuck in wrong 6. Reverse drrectron of compressor rotation.
7. Worn bearrngs. 7. Replace compressor.
8. Low oil level. 8. Add oil.
9. Loose fitting on oil lines. 9. Check and tighten system.
10. Pump housing gasket leaks. 10. Replace gasket.
11. Flooding of refrigerant into crankcase. 11. Adjust thermal expansion valve.
Compressor loses 1. Lack of refrrgerant.
1. Check for leaks and repair Add refrigerant.
oil 2. Excessive compression ring blow-by. 2. Replace compressor.
1. Low voltage during high load conditions. 1. Check supply voltage for excessive lrne drip.
2. Defective or grounded wring in motor. 2. Replace compressor motor.
3. Loose power wiring.
3. Check all connections and tighten.
4. High condensrng temperature. 4. See Corrective Steps for high discharge pressure.
relays or circuit 5. Power line fault causing unbalanced voltage. 5. Check supply voltage. Notify power compnay. Do not breakers open start until fault is corrected.
6. High ambient temperature around the over- 6. Provide ventilation to reduce heat.
7. Failure of second starter to pull in on part- 7. Repair or replace starter or time delay mechanism.
winding start systems.
1. Operating beyond design conditions.
Compressor thermal protector switch open.
2. Discharge valve partially shut.
3. Blown valve plate gasket.
I. Add facilities so that conditions are within allowable limits.
2. Open valve.
3. Replace gasket.
IN-WARRANTY RETURN MATERIAL PROCEDURE
Copeland Refrigeration Corporation has stocking wholesalers who maintain a stock of replacement compressors and service parts to serve refrigeration contractors and servicemen.
When a compressor fails in warranty, contact your local sales representative, or McQuay Warranty Claims Department at the address on the cover of this bulletin. You will be authorized to exchange the defective compressor at a Copeland Wholesaler, or an advance replacement can be obtained. A salvage credit is issued to you by the wholesaler on the returned compressor after Copeland factory inspection of the inoperative compressor. Provide McQuay with full details and invoices and we w i l l reimburse the difference. In this transaction, be certain that the compressor is definitely defective. If a compressor is received from the field that tests satisfactorily, a service charge plus a transportation charge will be charged against its original credit value.
On all out-of-warranty compressor failures, Copeland offers the same field facilities for service and/or replacement as described above.
The credit issued by Copeland on the returned compressor will be determined by the repair charge established for that particular unit.
Components Other Than Compressors
Material may not be returned except by permission of authorized factory service personnel of McQuay, Inc., at Mpls., MN. A "Return
Goods" tag will be sent to be included with the returned material.
Enter the information as called for on the tag in order to expedite handling at our factories and prompt issuance of credits.
The return of the part does not constitute an order for replacement.
Therefore, a purchase order must be entered through your nearest
McQUAY Representative. The order should include part name, part number, model number and serial number of the unit involved.
Following our personal inspection of the returned part, and if it is determined that the failure is due to faulty material or workmanship, and in warranty,credit will be issued on customer's purchase order.
All parts shall be returned to the pre-designated McQUAY factory, transportation charges prepaid.
Oil Pressure Safety Control
The oil pressure safety control is a manually resettable device which senses the differential between oil pressure at the discharge of the compressor oil pump and suction pressure inside the compressor crankcase. When the oil pressure reaches approximately 15 PSI above the crankcase suction pressure, the pressure actuated contact of the control opens from its normally closed position. If this pressure differential cannot be developed, the contact will remain closed and energize a heater element within the control. The heater element warms a normally closed bimetallic contact and causes the contact to open de-energizing a safety relay and breaking power to the compressor.
It takes about 120 seconds to warm the heater element enough to open the bimetallic contact thus allowing time for the pressure differential to develop.
If during operation, the differential drops below 10 PSI, the heater element will be energized and the compressor will stop. The control can be reset by pushing the reset button on the control. If the compressor does not re-start, allow a few minutes for the heater element and bimetallic contacts to cool and reset the control again.
To check the control, pump down and shutoff all power to the unit.
Remove the compressor fuses, and install a voltmeter between terminals "L" and "M" of the oil pressure control. Turn on power to the unit control circuit (separate disconnect or main unit disconnect depending on the type of installation). Check to see that the control stop switch (Sl) is in the "on" position. The control circuit should now be energized but with the absence of the compressor fuses,
no oil pressure differential can develop and thus the pressure actuated contacts of the control will energize the heater element and open the bimetallic contacts of the control within 120 seconds. When this happens, the safety relay is de-energized, the voltmeter reading will rise to 115V, and the compressor contactor should open. Repeated operations of the control will cause a slight heat buildup in the bimetallic contacts resulting in a slightly longer time for reset with each successive operation.
LINE (SEE NOTE 1) NEUTRAL
- HEATER ELEMENT
LINE (SEE NOTE 2)
BIMETALLIC CONTACTS SAFETY RELAY
1. Hot only when the unit thermostat calls for compressor to run.
2. Hot only when other safety control contacts are closed.
High Pressure Control
The high pressure control is a single pole pressure activated switch that opens on a pressure rise to de-energize the entire control circuit except for compressor crankcase heaters. It senses condenser pressure and is factory set to open at 380 PSIG and can be manually reset closed at 315 PSIG. To check the control, either block off condenser surface or start the unit with fuses in only one fan fuse block (FBll) and observe the cut-out point of the control by watching condenser pressure rise. The highest point reached before cutout is the cut-out setting of the control.
CAUTION: Although there is an additional pressure relief device in the system set at 425 PSIG, it is highly recommended that the "control stop" switch (Sl) be close at hand in case the high pressure control should malfunction.
Low Pressure Control
The low pressure control is a single pole pressure switch that closes on a pressure rise. It senses evaporator pressure and is factory set to close at 60 PSIG and automatically open at 25 PSIG.
The control has an adjustable range of 20 in. of Hg.
to 100 PSIG and an adjustable differential of 6 to 40 PSIG. To check the control (unit must be running), move the pumpdown switch(es) (PSl and PS2) to the "man.
pumpdown" position. As the compressor pumps down condenser pressure will rise and evaporator pressure will drop. The lowest evaporator pressure reached before cut-out is the cut-out setting of the control.
By moving the pumpdown switch(es) (PSl and PS2) to the "auto. pumpdown" position, evaporator pressure will rise. The highest evaporator pressure reached before compressor re-start is the cut in setting of the control.
- Head Pressure Control
Fantrol is a system for progressively turning on or off condenser fans when they are no longer required. This is done to reduce condenser capacity (typically in low outdoor ambient temperatures) and is accomplished by a combination of pressure and temperature actuated controls. The first fan (No.
11) is started by its contactor when the first compressor in the unit starts. The second fan (No. 12) is controlled by a pair of parallel wired pressure switches, one of which senses condenser pressure in refrigerant circuit No. 1, and one which senses pressure in refrigerant circuit No. 2. The third fan (No.
13-3 fan units only) is controlled by a pair of parallel wired temperature switches, one of which senses condenser air inlet temperature for refrigerant circuit No. 1 and one for circuit No. 2.
Pressure temperature control set points are indicated below.
WITH COMPRESSOR WITH COMPRESSOR
To check the cut-in points of the controls, the unit must initially be off. With the unit prepared for start up according to the procedures outlined in this bulletin, move pumpdown switches (PSl & PS2) to the "auto. pumpdown" position. Evaporator pressure will begin to rise and the compressor(s) should start with fan No. 11 starting immediately. After the compressor(s) starts, observe condenser pressure as it rises. When the condenser pressure reaches approximately
270 PSIG, contactor Ml2 should pull in to start fan No. 12. On 3 fan units, fan No.
13 should start via contactor Ml3 whenever the ambient air at the condenser inlet reaches 80F.
It may be difficult to check the cut-out point of fan No. 13 (on 3 fan units) at the instant it happens, but it should be off whenever the ambient air at the condenser inlet is below 70F.
To check the cut-out point of fan No. 12, some means of reducing the load on the unit must be available or the fan operation and condenser pressure(s) must be observed as the load drops off naturally. When the condenser pressure drops to approximately 170 PSIG, contactor Ml2 should drop out to turn off fan No. 12.
Dampertrol - Optional Head Pressure Control
Dampertrol is an optional system for reducing condenser capacity. It consists of an assembly of damper blades, linkages and blade operators installed over the first fan turned on by Fantrol (Fan No. 11) and arranged to operate as shown. The blade operators sense condenser pressure and extend or contract in response to the pressure to open or close the damper blades as required to maintain adequate condenser pressure. The operators are factory set to begin opening the damper blades at 170 + 5 PSIG and to be fully open at 250 2 10 PSIG.
To check the damper blade operator pressure settings, the unit should be started with the fuses removed from fans 11 and 13 (on 3 fan units only). At condenser pressures below 170 & 5 PSIG, the damper blades should be completely closed. As pressure rises above 170 & 5 PSIG, the damper blades should begin opening and be fully open at 250 +_
10 PSIG. Leaving the fuses in on fan 12 will prevent head pressure from becoming excessive since this fan will start after the fully open setting of the damper operators has been observed.
DAMPERTROL IN OPEN POSITION
DAMPERTROL IN CLOSED POSITION page 46
Part Winding Start - Optional
Part winding start is available on all voltage units and consists of a solid state time delay wired in series with the contactor that energizes the 2nd winding of each compressor motor.
Its purpose is to limit current in-rush to the compressors upon start up. As each compressor starts, the contactor for the first motor winding is energized instantly while that for the second motor winding is delayed for 1 second.
Control checkout is best accomplished by observation as each contactor is pulled in to see that the 1 second delay occurs before the second contactor pulls in.
TIME DELAY 1
(1st MOTOR WINDING)
LINE .-%.., NEUTRAL
(2nd MOTOR WINDING)
Low Ambient Start - Optional
Low ambient start is available on all units as an option with Fantrol and included automatically with optional Dampertrol. It consists of a solid state normally closed time delay wired in series with a relay.
These are both wired in parallel to the liquid line solenoid valve so that when the solenoid valve is energized by the unit thermostat, the low ambient start relay is also energized through the time delay.
The relay has contacts that essentially short circuit the low pressure control and allow the compressor to start with the low pressure control open.
After about 2 3/4 minutes, the time delay will open and de-energize the relay. If the system has not built up enough evaporator pressure to close the low pressure control, the compressor will stop. The time delay can be reset to its original normally closed position by moving the pumpdown switch(es) (PSl or PS2) to the "man. pumpdown" position. Moving the pumpdown switch back to the "auto. pumpdown" position will again energize the relay for another attempt at start up . If the system has built up enough evaporator pressure, the compressor will continue to run.
To check the control, turn off all power to the unit and remove the wire(s) (No.
113 & 213) leading to the low pressure control(s) (LPl
& LP2) from terminal 4 in the unit control center.
Remove the compressor fuses and jumper across terminals L & M of the freeze controls(s) and oil pressure safety control(s).
Energize the control circuit by turning on the control circuit disconnect or main power disconnect (depending on the installation) and the control stop switch Sl. The compressor contactors should pull in instantly.
NOTE: Line is only hot when the unit thermostat calls for compressor to run.
Compressor Lockout - Optional
Compressor lockout consists of a solid state time delay wired in series with the compressor contactor(
Its purpose is to prevent rapid compressor cycling when cooling demands are erratic.
The circuit illustrated above is for the lead compressor in each refrigerand circuit. The circuit for the second compressor(s) performs the same function but is wired differently (see unit wiring diagram).
When the unit thermostat no longer calls for cooling and the compressor contactor have opened, the lockout time delay breaks open the circuit preventing compressore re-start.
The circuit remains open for a period of 5 minutes so that if the unit thermostat should call for cooling before the delay period has expired, the compressor will not re-start.
After 5 minutes, the time delay will close its contacts to complete the circuit and be ready for start up. The time delay opens its contacts whenever power to terminal 4 is interrupted and resets closed automatically after the time delay period.
To check the control, the compressor(s) must be running initially.
Move the pumpdown switch (PSl or PS2) to the "man. pumpdown" position. Immediately after the compressor(s) have stopped running, move the pumpdown switch back to the "auto. pumpdown" position.
The lead compressor should not re-start for 5 minutes.
The second compressor in the refrigerant circuit should start approximately 20 seconds after the lead compressor, high enough to require it.
provided that the cooling load is
Each refrigerant circuit can be checked the same way.
(SEE NOTE) -
TIME DELAY x-k-
TO UNIT THERMOSTAT
NOTE: Hot whenever freeze control and high pressure control permit safe operation.
Alarm Bell - Optional
The 24 volt alarm bell is mounted inside the control center but not wired to the control circuit. It is expected that in most cases, the customer will want to relocate the bell where it will be more easily heard in the event of a safety failure. There are leads for connection of the bell inside a junction box which is located in the unit control center. All that is necessary is that the bell be mounted in a preferred location and wired to the leads in the junction box.
The bell is wired into the control circuit so that it will sound whenever there is a failure due to low oil pressure, motor overload, or excessive condenser pressure.
Hot Gas Bypass - Optional
Hot gas bypass is a system for maintaining evaporator pressure at or above a minimum value. The purpose for doing this is to keep the velocity of the refrigerant as it passes through the evaporator high enough for proper oil return to the compressor when cooling load conditions are light.
The system usually consists of a solenoid valve piped in series with a pressure regulating valve as shown. Units are available with optional hot gas connection with a manual shutoff valve and capped stub.
A hot gas bypass kit consisting of a 115 volt solenoid valve and a pressure regulating valve is available from McQuay under ordering number 886-321262B-02 for ALP units 067AS/D through 159AD.
The solenoid valve should be wired to open whenever the unit t h e r m o stat calls for the first stage of cooling (see Figure 10). The pressure regulating valve that McQuay offers is factory set to begin opening at 58 PSIG (32F for R-22) when the air charged bulb is in an 80F ambient temperature. The bulb can be mounted anywhere as long as it senses a fairly constant temperature at various load conditions. The compressor suction line is one such mounting location.
It is generally in the 50F to 60F range. The chart on page 50 indicates that when the bulb is sensing 50F to 60F temperatures, the valve will begin opening at 54 to 56 PSIG. This setting can be changed as indicated above, by changing the pressure of the air charge in the adjustable bulb. To raise the pressure setting, remove the cap on the bulb and turn the adjustment screw clockwise. To lower the setting, turn the screw counter-clockwise. Do not force the adjustment beyond the range it is designed for as this will damage the adjustment assembly.
The regulating valve opening point can be determined by slowly reducing the system load while observing the suction pressure. When the bypass valve starts to open, the refrigerant line on the evaporator side of the valve will begin to feel warm to the touch.
CAUTION: The hot gas line may become hot enough to cause injury in a very short time so care should be taken during valve checkout.
On installations where the condensing unit is remote from the evaporator, it is recommended that the hot gas bypass valve be mounted near the condensing unit to minimize the amount of refrigerant that will condense in the hot gas line during periods when hot gas bypass is not required.
The expansion valve, like the solenoid valve, should not normally require replacement, but if it does, the unit must be pumped down by using the manual liquid line shutoff valve. If the problem can be traced to the power element only, it can be unscrewed from the valve body without removing the valve but only after pumping the unit down with the manual liquid line shutoff valves.
HOT GAS BYPASS PIPING
DIAGRAM HOT GAS BYPASS ADJUSTMENT RANGE
OTE BULB A D J U S T M E N T R A N G E
I I I I I
Hot Gas Bypass
Connection to Suction
Side of Evapoator
T E M P ioFI AT BULB LOCATION
p a g e 5 0
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project