12 WGZ030D through WGZ200D OMM 1130
11. Set pumpdown switches PS1 and PS2 to “auto” for restart and normal operation.
12. Start the system by setting the system switch S1 to on.
13. After running the unit for a short time, check the oil level in each compressor crankcase, rotation of
condenser fans (if any), and check for flashing in the refrigerant sight glass.
14. After system performance has stabilized, it is necessary that the “Compressorized Equipment
Warranty Form” (Form No. 206036A) be completed to establish commencement of the warranty
period. Be sure to list the pressure drop across both vessels. This form is shipped with the unit and
after completion should be returned to McQuay Service Department through your sales
representative.
Weekend or Temporary Shutdown
Move pumpdown switches PS1 and PS2 to the “manual pumpdown” position. After the compressors have
pumped down, turn off the chilled water pump. Note: With the unit in this condition, it will not restart
until these switches are turned back on. The unit has one-time pumpdown. It is important that the
compressors pump down before the water flow to the unit is interrupted to avoid freeze-up in the
evaporator.
Leave S1 on and power to the unit so that the crankcase heaters will remain energized.
Start-up after Temporary Shutdown
1. Start the water pumps.
2. With the control system switch S1 in the “on” position, move the pumpdown switches PS1 and PS2
to the “auto pumpdown” position.
3. Observe the unit operation for a short time, noting unusual sounds or possible cycling of compressors.
4. Check compressor crankcase heaters.
Extended Shutdown
Close the manual liquid line shutoff valves.
After the compressors have pumped down, turn off the water pumps.
Turn off all power to the unit.
Move the control service switch S1 to the “off” position.
Close the discharge shutoff valves on the compressor(s) and the liquid outlet valves at the condenser.
Tag all opened disconnect switches to warn against start-up before opening the compressor suction
and discharge valves.
Drain all water from the unit evaporator, condenser, and chilled water piping if the unit is to be shut
down during the winter and exposed to below freezing temperatures. Do not leave the vessels or
piping open to the atmosphere over the shutdown period.
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