Split system startup, Attention installer, Compressor precautions – ClimaCool UCR 30, 50 and 70 tons Manual User Manual
Page 42
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42
Split System Startup
Once installation is complete, check the following:
•
All refrigerant and electrical connections must be tight.
Tighten all loose wire terminal connections that may
have loosened in shipping.
•
The compressor oil is at the proper level in the oil sight
glass for the compressor being used (See page 50 -
Compressor Information).
•
Check initial settings of thermostats and pressure
controls. All adjustable pressure controls and valves will
require a fi nal adjustment with the use of a compatible
gauge.
•
Check the control panel to be sure that all wiring is in
accord with the unit wiring diagram.
•
Check all three phase motors for proper rotation.
Compressor Precautions
Care must be taken when initially starting a system or
when the system has been off for an extended period. At
this time, the compressor may contain liquid refrigerant.
Simply starting the system and walking away may result
in irreparable compressor damage not covered under
warranty. To prevent compressor damage, one or more of
the following steps may be used:
Step 1: All compressors are supplied with a crankcase
heater. It must be activated 24 hours prior to starting the
compressor. Be sure to check that the heater is functional.
This can be done by simply touching the compressor in the
area of the heater. It should feel warm to the touch. This
check should be performed shortly after energizing the
heater and again prior to starting the compressor. If the
compressor is cold, do not attempt to start it. Locate the
source of the problem, correct it and wait 24 hours before
starting the compressor.
Step 2: Use a safe heat source such as a heat lamp on the
compressor crankcase for approximately 1/2 hour before
startup. Never use a torch or heat gun. They can raise
system pressures to dangerous levels in a very short time
resulting in injury to personnel as well as property damage.
Step 3: After following steps 1 and 2 above you can be
relatively certain that no liquid refrigerant is left in the
compressor. This does not mean that liquid refrigerant is
not present elsewhere in the low side. To avoid compressor
damage on startup, deactivate the liquid solenoid and
“bump” the compressor, using the controller “POWER”
switch, several times. The fi rst 2 or 3 times the compressor
is “bumped” it should not be allowed to run more than 2
or 3 seconds. Increase the run time to 5, 10 and 15 seconds
over the next 3 “bumps”. This will rapidly reduce low side
pressure causing any liquid to boil off quickly. At this point it
is usually safe to allow the compressor to run.
Step 4: After starting the compressor, listen for unusual
sounds such as knocking. Should they be heard, immediately
stop the compressor. Do not restart until the problem is
resolved. While scroll compressors are more tolerant to
liquid refrigerant than reciprocating types of compressors,
the above precautions should still be observed. Rotational
direction is very important with three phase scroll
compressors. Running these compressors with reversed
rotation will result in damage not covered by warranty.
When starting a three phase scroll compressor, refrigerant
pressure gauges must be attached to both the high and
low pressure ports provided on the system. With the
compressor rotating in the proper direction, system suction
pressure should drop and discharge pressure should
rise to appropriate levels within a few seconds after the
compressor is stated. If this is not the case, the compressor
is probably running in reversed rotation. Each chiller is
computer tested and all three phase motors, (pumps and
compressors) are in proper phase when it leaves the factory.
Turn the power off at the main disconnect and reverse any
two of the three main power leads and restart. Observe
the suction and discharge pressure gauges to verify that
the compressor is rotating correctly. If pressures are still
not appropriate, some other problem has developed which
must be found and corrected prior to running the system.
ATTENTION INSTALLER
3 Phase Scroll Compressor Units
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