McQuay seasoncon ALP-067A Installation And Maintenance Data page 38

Temporary Shut-Down
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.
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.
3.
Observe the unit operation for a short time to be sure that the
compressors do not cut out on low oil pressure.
Extended Shut-Down
1.
Close the manual liquid line shutoff valves.
2.
After the compressors have pumped down, turn off the chilled
water pump or evaporator fan.
3. Turn off all power to the unit and to the auxiliary equipment.
4.
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 be-
fore opening the compressor suction and discharge valves.
Start-Up After Extended Shut-Down
1. Inspect all auxiliary equipment (pumps, fans, etc.) to see that
each device is in satisfactory operating condition.
2.
Remove all debris that has collected on the surface of the con-
denser coils.
3. Open the compressor suction and discharge valves.
4.
Open the manual liquid line shutoff valves.
5.
Check to see that pumpdown switches (PSl 6; PS2) are in the "man.
pumpdown" position.
6. Turn on the electric power to the unit and other parts of the
system.
7. Allow the crankcase heaters to operate for at least 8 hours prior
to start-up.
8. On chilled water installations, start the chilled water pump and
purge the water piping as well as the evaporator.
9.
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
"auto. pumpdown" position.
11.
After running the unit for a short time, check the oil level in
each compressor crankcase and check for flashing in the refri-
gerant sight glass.
page 38
It is especially important on chilled water