
54
Weight of Refrigerant in Evaporator plus
Condenser for VS Compressors
Model
Starting Charge (lbs.)
GUAX-022XX
15
GUAX-036XX
25
GUAX-045XX
32.5
GUAX-070XX
25
GUAX-091XX
32.5
GUAX-125XX
37.5
2. Add the amount of refrigerant needed for the evaporator and condenser plus the line-set
volume
5.4 Line Set Charge Calculations
3. Next connect the refrigerant tank to the refrigerant manifold gauge set and make sure the
manifold gauge set is properly purged.
4. From a vacuum, slowly open the high side liquid line valve on the refrigerant manifold gauge
to feed liquid refrigerant through the high side.
5. Add the calculated amount of refrigerant.
At this point there will be approximately 70-80% of the total charge in the system. It is likely that
more refrigerant will be required to complete the charging procedure. Close the valve on the
refrigerant manifold gauge set.
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.
5.7.1.4.
Charge Variable Speed Compressor
The variable speed compressor requires a little more care while charging. All unit safeties must
be active while charging the compressor. Start the system by changing the Temperature
Setpoint under Menu B
– Setpoints on the dap4 controller. The unit must be started in the normal
operating mode based on a call for cooling required by the dap4 controller once an initial charge
has been added to the circuit. Before starting the system, make sure pressure gauges and
suction line temperature sensor are hooked up and refrigerant readings are aligned with EEV
reading. For dual circuit units, remove the fixed speed c
ompressor’s fuses to prevent it from
starting.
If the unit is in OFFbyKEY position, hold the “Esc” key for 5 seconds to start the system via the
dap4 controller. The return air temperature needs to be higher than temperature setpoint plus
deadband for the compressor to start.
Example:
Existing return air temperature is 75
F (24
C) , set the dap4 Temperature Setpoint to
65
F (18
C). The variable speed compressor will start and run at a full speed.