Temporary Shutdown And
Restart
To shut the unit down for a short
time, use the following procedure:
1 Press the STOP key on the UCM-
CLD. The compressors will
continue to operate and, after
unloading for 20 seconds, will stop
when the compressor contactors
de-energize.
Note: On Free-Cooling units in Free
Cooling mode, only the fans will
stop. In Compressor mode, there is
no change.
2 Stop the water circulation by
turning off the chilled water pump.
To restart the unit after a
temporary shutdown, enable the
chilled water pump and press the
AUTO key. The unit will start
normally, provided the following
conditions exist:
❏ The control module receives a call
for cooling and the differential-to-
start is above the setpoint.
❏ All system operating interlocks
and safety circuits are satisfied.
Extended Shutdown
Procedure
The following procedure is to be
followed if the system is to be taken
out of service for an
extended period of time, e.g.
seasonal shutdown:
1 Test the unit for refrigerant leaks
and repair as necessary.
2 Open the electrical disconnect
switches for the chilled water
pump. Lock the switches in the
"OPEN" position.
CAUTION! Lock the chilled water
pump disconnect Switch in the
"OPEN" position, to prevent pump
damage.
3 Close all chilled water supply
valves. Drain the water from the
evaporator.
4 Open the unit main electrical
disconnect and unit-mounted
disconnect (if installed) and lock on
the "OPEN" position.
CAUTION! Lock the disconnects in
the "OPEN" position to prevent
accidental start-up and damage to
the system when it has been setup
for extended shutdown.
5 At least every three months
(quarterly), check the refrigerant
pressure in the unit to verify that
the refrigerant charge is intact.
Note: For Free-Cooling units, check
the percentage of ethylene glycol in
the water circuit in order to protect
against freeze-up.
74 RTAD-SVX01F-E4
Unit Shutdown Procedures
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