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Do not start the system while in a vacuum. Do not leave the system unattended until normal operating conditions
are achieved.
•
Operate the system for a minimum of two hours and perform checks of the following:
Check the compressor discharge and suction pressures to ensure they are in the normal operating range.
o
Check the liquid line sight glass for proper refrigerant charge (based off of 105ºF condenser coil).
o
•
Monitor the compressor oil level (semi-hermetic compressors), add oil as necessary to keep the level at ¾ sight glass
when idle and ½ sight glass when running.
•
Check the voltage and amperage at the compressor terminals. Voltage must be within +10% or -5% of the rating
indicted on the condensing unit name plate. On three phase compressors, verify there is a balanced load.
•
Check all fans on the evaporator coil and condensing unit to be sure they are operational and turning in the correct
direction.
Check the piping and electrical connections for vibration. Add supports and strapping if needed.
•
•
Check the crankcase heater operation (if equipped).
•
Set the defrost control time and verify the defrost initiation settings. See pages 28-30 for additional details.
•
Set temperature control to desired temperature range.
•
Check the compressor and evaporator superheat (reference pages 21-23).
•
After all system checks have been checked, properly adjusted, and verified, replace all Schrader caps, service valve
caps, electrical box covers, housings, etc. File a copy of this manual for future reference.
Failure to check and properly adjust compressor superheat can result in premature system failure.
Compressor Superheat
•
Compressor superheat is a critical value that must be checked. Check the compressor superheat as follows:
Determine the suction pressure at the suction service valve of the compressor.
o
Determine the saturation temperature at the observed suction pressure using refrigeration pressure
o
temperature tables.
Measure the suction line temperature 6 -10 inches away from the compressor.
o
Subtract the saturation temperature (step 2) from the measured temperature (step 3). The difference is the
o
superheat of suction gas.
•
A low suction superheat can cause liquid to return to the compressor. This will cause dilution of the oil and eventual
failure of the bearings, rings and valves.
•
A high suction superheat will cause excessive discharge temperatures, which cause a breakdown of the oil. This
causes piston ring wear, and piston and cylinder wall damage.
•
System capacity decreases as the suction superheat increases.
•
For maximum system capacity, keep the suction superheat as low as practical. Copeland requires a minimum
compressor superheat of 20°F; however, to improve compressor life, 25°F to 40°F is preferred.
•
Adjust the expansion valve at the evaporator when adjustments to the suction superheat are necessary.
•
Refer to "Evaporator Superheat" on the next 2 pages for more information.
CAUTION
CAUTION
16
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