10-2014 gForce User Manual ● 37
Note:
Charging to a full liquid line sight glass should never be the sole
means of determining the correct refrigerant charge. Other parameters
such as superheat, suction pressure, head pressure, sub-cooling and
ambient temperature are also important. A system charged to a clear sight
glass is often overcharged.
5.3.2 Flooded System Charging
Flooded systems are supplied with optional liquid receiver and head pressure control
valve. When the ambient temperature falls during cold weather, the head pressure
control valve will regulate the flow of refrigerant to ensure minimum receiver pressure.
The condenser is partially flooded with liquid refrigerant in cold weather. In warm
weather the extra refrigerant is stored in the receiver.
Flooded systems require more refrigerant than fan speed control systems. Connect the
pressure gauge manifold set to the high and low ports near the compressor. Connect
the charging line to the refrigerant tank and set for liquid feed. Open the refrigerant
tank valve and purge the line. Open the high side valve on the manifold only and allow
the refrigerant to flow until the system pressure equalizes. At this point the system will
have 75 to 85% of the total refrigerant charge.
5.3.2.1 Constant Speed Compressor
Start the evaporator fan. From a vacuum, add liquid refrigerant to the high side of the
system until the pressures equalize. Start the compressor.
NOTE:
A quick and easy way to run the fans and compressor is by using
the manual slide switches provided by the Manual Override Module (3.12
Manual Override Switches). Switch the fan and compressor manual
switches to the ON position. All automatic control is disabled but safety
switches will remain functional.
WARNING:
Before starting a compressor, the crankcase heater should be
energized for a minimum of 12 hours to reduce the possibility of liquid
slugging on start-up. Failure to energize the crankcase heater could result
in compressor damage. If the system is charged from a vacuum, the
preheating of the compressor is not necessary.
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