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START-UP PROCEDURE

Do not start the SEASONPAK water chiller until the

following steps have been completed.

Check all auxi liary components of the installation.

3.

4.

5.

Open the compressor suction and discharge shut
off valves until back seated. Back seating the
valve closes the gauge ports and, if gauges ore
provided, close valve one turn from full open, to-
ward the closed position. Always replace seal
caps.
Open the manual liquid line shut off valve at the
condenser.

If water regulating valves are provided, connect

their capillary to the manual valves provided on
the condensers and open the manual valves.
Check to see that the water temperature thermo-

stat is installed in the entering water line, that

6

7.

8.

9.

10.
11.
12.

13.

the thermostat well is full of heat conducting
compound and that the bulb is secured with the
retaining fitting.
Check the compressor oil level. Prior to start-up,
the oil level should be in the oil sight-glass.

Fill the water system. The cooler circuits should
be filled with clean non-corrosive water.
Check the main system “on-off” switch to see
that it is in the “off” position. The pump down
switches should be thrown to the “auto” position.
Check resets of all safety controls.
Throw the main power disconnect to “on”.
Start the auxiliary equipment for the installation.
Set the circuit breakers to “on”
Start the system by pushing the system “on-off”
rocker switch to “on”.

OPERATION

During full load operation, check the compressor oil

level. It should be at the center of the oil sight glass

during operation.

Check the refrigerant charge frequently at the mois-

ture/liquid indicator. A steady clear glass of liquid
r e f r i g e r a n t indicates sufficient charge. The sight
glass also indicates the moisture content of the refrig-
erant in the system. The color of the element in the

glass indicates whether the system is wet or dry. Refer
to the color table on face or cap of the indicator. If
the indicator does not show a dry system after several

hours of operation, the filter-drier element must be

c h a r g e d .

CHECKING

All controls are checked a n d  adjusted prior to leaving

the factory. However, after the unit has operated sat-

isfactorily for a reasonable length of time, a check of

the operation and safety controls can be made as in-

dicated below.

Oil Pressure Safety Switch - The oil failure pressure
switch is activated by a low pressure differential be-

tween the oil pressure and the crankcase pressure.

Upon start-up, the normally closed pressure actuated
contact of this control opens when the pressure dif-
ferential increases to about 15 psig. If oil pressure
does not reach this differential, the thermal time de-

lay remains energized and opens a bi-metallic safety
contact, de-energizing the complete control circuit.
If pressure reaches the prescribed differential within
120 seconds, the thermal time delay is de-energized

and the control circuit remains closed. If, during the
operation, the oil pressure differential falls below 10

psig, the thermal time delay is again energized ond

and the control will shut down the compressor.

To check the control, jumper the Freezestat ter-

minals L & M and trip the circuit breaker to the “off”
position. Throw control circuit to “on” to pull-in
contactor. The contactor should drop out ond the safe-
ty indicator light should go out after approximately

120 seconds or less. After checking the control, wait

approximately 2 to 3 minutes and then reset control

manually. The compressor con then be started. Re-
peated successive operations of the control will re-

quire a longer period before it can be reset, since the

bi-metal will get hotter and will take more time to

cool.

Check the temperature control thermostat by observ-

ing operation at reduced loads. The thermostat is fac-

tory set for 44F leaving chilled water temperature
w h e n   t h e   e n t e r i n g   t e m p e r a t u r e   i s   5 4 F .   R e f e r   t o

CHECKING CONTROLS section, below.

Check voltage and amperage of the compressor

motor.

Adjust water regulating valve for discharge pres-

sures between 200 and230 psig for the most economic-

al operating pressure.

Close gauge ports on valves when gauge readings

are not required. This will prolong the gauge life.

CONTROLS

High Pressure Control - The high pressure switch

will shut down the compressor and close the liquid

line solenoid valve when the compressor discharge

pressure reaches 270 psig for water cooled units, or

380 psig for air cooled units. To check the control,

slowly throttle the condenser inlet water or shut down
the condenser fan. Observe the cut-out point. During
testing, stand by the System “On-Off” switch to shut
down the unit should the safety device malfunction.

Be sure the gauges used ore accurate.

The water cooled condensers are supplied with a

300 psig relief valve and the discharge pressure dur-

ing the test must be kept below 270 psig. For air

cooled 

condenser operation, the relief valve will be

set for 425 psig.

The control can be manually reset at approximately

70 psig below the cut out point.

Low Pressure Control - This pressure switch is con-

nected 

to the low side of the system and its purpose

is to shut down the compressorot the end of the pump-
down cycle. It will open at 35 psig and automatically
reset at approximotely 60 psig. The control can be
checked by throwing the individual pumpdown switches

to the manual position ond observing the cut-out point
on the gauge.

Freezestat - The Freezestat is a pressure type con-

trol connected to the low side of the system and is set
to shut down the system when the pressure drops low
enough to be dangerous 

OS 

far as cooler freeze-up is

concerned. The control is factory set at 52 to 53 psig.
When dropping to this point, the normally open pres-
sure actuated contacts of this control will close ener-

Page 24

Summary of Contents for Seasonpak PWA-008A

Page 1: ...BLE OF CONTENTS CONTROLS CHECKING 24 CROSSREFERENCE NEW TO OLD MO 2 ELECTRICAL 22 23 CONTROL CENTER SERVICE 26 27 ELECTRICALDATA 22 23 WIRING 10 13 WIRING DIAGRAMS 14 21 MAINTENANCE 26 29 MOVING PLACI...

Page 2: ...LL UNIT FROM ANYTHING OTHER THAN water cooled condensers Arrangement 1 is supplied THE BASE MOVING AND PLACING THE UNIT MOVING THE UNIT The McQUAY SEASONPAK water chiller is mounted on heavy wooden sk...

Page 3: ...EARANCE FOR COOLER TUBE RE MOVAL MEASURED FROM CENTER LINE OF CHILLED WATER CONNECTION ON EITHER END TABLE NO 1 MINIMUM CLEARANCE UNIT SIZE I MINIMUM CLEARANCE 007A THRU 015A 72 020A THRU 041A 96 050A...

Page 4: ......

Page 5: ......

Page 6: ...nded beyond the pro FIGURE NO 7 TO COOI ER 4 posed insulation thickness to make them accessible CHILLED WATER THERMOSTAT WHR 008A thru 060A The chilled water thermostat is mounted inside the control c...

Page 7: ...oop at the outlet end is recommended See Figure 9 WATER REGULATING VALVES EACH CONDENSER FIGURE NO 8 3 WAY WATER REGULATING VALVES COi lNG TOWER PURGE 4 MAIN CONDENSER WATER SUPPLY FROM PUMP BY PASS B...

Page 8: ...cal discharge riser is too low considerable oil may collect in the riser and the horizontal header causing the compressor to lose its oil and resultant damage due to lack of lubrication Another danger...

Page 9: ...E NO 11 PURGE VALVE DISCHARGE LINE HECK VALVE LIQUID LINE FIGURE NO 13 DISCHARGE LINE I TO EVAPORATOR RECEIVER LrQuro LINE EVAPORATORS or and receiver The discharge line piping in this case is not too...

Page 10: ...TAT 12 INDICATOR LIGHTS 6 HIGH MANUAL RESET AND LOW PRESSURE CUTOUTS 7 CONTROL SYSTEM ON OFF SWITCH FIGURE NO 16 MODELS WHR 070A THRU 120A 1 FREEZESTAT MANUAL RESET 7 CONTROL SYSTEM ON OFF SWITCH 2 OI...

Page 11: ...020A THRU 060A FIGURE NO 17 TOP VIEW OF UNIT Models WHR OO8A thru 015A are single compressor units 3 4 5 6 7 8 9 10 25 The power from 25 is fed thru NC contacts to relay R3 and R4 to energizethe compr...

Page 12: ...e operating before power can be applied to start this system Note that the crankcase heaters will be energized regard less of water flow The flow switch is recommended and does not have the shortcomin...

Page 13: ...itch LP1 opens Contactors Ml M3 and relay R3 will open and compressor 1A will turn off and stay off until relay R1 is again energized thru the thermostat In the event compressor 1A is off on oil press...

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Page 24: ...aches the prescribed differential within 120 seconds the thermal time delay is de energized and the control circuit remains closed If during the operation the oil pressure differential falls below 10...

Page 25: ...d unloading sequence of the unit based on a full load cooling range of 10F It should be realized however that there will be a fluctuation in the leaving water temperature as the unit cycles unloads an...

Page 26: ...eaning of the finned surface of the conden ser coil Cleaning may be accomplished by using a cold water spray brushing vacuuming or high pres sure air No tools should be used that could damage the coil...

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Page 28: ...s t e m c P u r g e t h e n o n c o n d e n s i b l e s d S y s t e m o v e r c h a r g e d w i t h r e f r i g e r a n t d R e m o v e e x c e s s e D i s c h a r g e s h u t o f f v a l v e p a r t...

Page 29: ...n d t i g h t e n s y s t e m k R e p l a c e g a s k e t I Adjust t h e r m a l e x p a n s i o n v a l v e C o m p r e s s o r l o s e s o i l _ _ _ a L a c k o f r e f r i g e r a n t a C h e c k f...

Page 30: ...ber and serial number of the date of installation of the unit and date of failure along with an explanation of the malfunctions and a the unit as stamped on the serial plate attached to the unit If re...

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