www.DaikinApplied.com 93 IOM 1322 • WATER-COOLED SCROLL COMPRESSOR
Move pumpdown switches PS1 and PS2 to the “manual
pumpdown” position. After the compressors have pumped
down, turn o 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 ow 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.
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.
1. Close the manual liquid line shuto valves.
2. After the compressors have pumped down, turn o the
water pumps.
3. Turn o all power to the unit.
4. Move the control service switch S1 to the “o” position.
5. Close the discharge shuto valves on the compressor(s)
and the liquid outlet valves at the condenser.
6. Tag all opened disconnect switches to warn against
startup before opening the compressor suction and
discharge valves.
7. 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.
1. Inspect all equipment to see that it is in satisfactory
operating condition.
2. Remove all debris that has collected on the surface of
the condenser coils (remote condenser models) or check
the cooling tower, if present.
3. Open the compressor discharge valves until backseated.
Always replace valve seal caps.
4. Open the manual liquid line shuto valves.
5. 5 Check circuit breakers. They must be in the “o”
position.
6. Check to see that the pumpdown switches PS1 and PS2
are in the “manual shutdown” position and the control
system switch S1 is in the “o” position.
7. Put the main power and control circuit disconnects to the
“on” position.
8. Leak test the unit.
9. Allow the crankcase heaters to operate for at least 12
hours prior to start-up.
10. Start the chilled water pump and purge the water piping
as well as the evaporator in the unit.
11. Start the system auxiliary equipment for the installation
by turning on the time clock, ambient thermostat and/or
remote on/o switch.
12. Check that the MicroTech II controller is set to the
desired chilled water temperature.
13. Check resets of all equipment protection controls.
14. Switch the unit circuit breakers to “on.”
15. Start the system by setting the system switch S1 to “on.”
CAUTION
Most relays and terminals in the control center are powered when S1 is
closed and the control circuit disconnect is on. Therefore, do not close S1
until ready for start-up or serious equipment damage can occur.
16. Set pumpdown switches PS1 and PS2 to the “auto
pumpdown” position for restart and normal operation.
17. After running the unit for a short time, check the oil level
in the compressor oil sight glass or in the compressor’s
equalizing lines for ashing indicating possible refrigerant
in the oil (see System Maintenance section beginning on
page 100).
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