OM AGSD-1 75
CAUTION
The unit has a one-time pumpdown operation. When Q1 and Q2 are in the
"Pumpdown and Stop" position the unit will pump down once and not run
again until the Q1 and Q2 switches are moved to the auto position. If Q1 and
Q2 are in the auto position and the load has been satisfied, the unit will go
into one-time pumpdown and will remain off until the MicroTech II control
senses a call for cooling and starts the unit.
CAUTION
Water flow to the unit must not be interrupted before the compressors pump
down to avoid freeze-up in the evaporator.
CAUTION
If all power to the unit is turned off, the compressor heaters
will become inoperable. Once power is resumed to the unit,
the compressor and oil separator heaters must be energized a minimum of
12 hours before attempting to start the unit.
Failure to do so can damage the compressors due to excessive accumulation
of liquid in the compressor.
Start-up After Temporary Shutdown
1. Insure that the compressor and oil separator heaters have been energized for at least 12
hours prior to starting the unit.
2. Start the chilled water pump.
3. With System switch Q0 in the "on" position, move pumpdown switches Q1 and Q2 to
the "auto" position.
4. Observe the unit operation until the system has stabilized.
Extended (Seasonal) Shutdown
1. Move the Q1 and Q2 (and Q3) switches to the manual pumpdown position.
2. After the compressors have pumped down, turn off the chilled water pump.
3. Turn off all power to the unit and to the chilled water pump.
4. If fluid is left in the evaporator, confirm that the evaporator heaters are operational.
5. Move the emergency stop switch S1 to the "off" position.
6. Close the compressor discharge valve and the optional compressor suction valve (if so
equipped) as well as the liquid line shutoff valves.
7. Tag all opened compressor disconnect switches to warn against start-up before opening
the compressor suction valve and liquid line shutoff valves.
8. If glycol is not
used in the system, drain all water from the unit evaporator and chilled
water piping if the unit is to be shutdown during winter and temperatures below -20F
can be expected. The evaporator is equipped with heaters to help protect it down to
-20F. Chilled water piping must be protected with field-installed protection. Do not
leave the vessels or piping open to the atmosphere over the shutdown period.
9. Do not
apply power to the evaporator heaters if the system is drained of fluids as this
can cause the heaters to burn out.
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