47
WARNING:
Before applying facility power to the unit, the fuses to the
VFD (if equipped) and the fixed speed compressor(s) must be removed
to prevent compressor starting inadvertently/automatically.
When ready to start the charging procedures, remove facility power and
replace the fuses.
5.2.
General Pre-Charging Guidelines
•
Check the unit nameplate for refrigerant type to be used.
•
The unit must be piped and wired correctly for operation.
•
Always use a scale to weigh in the calculated refrigerant charge listed in tables in individual
compressor charging sections before starting the unit, record system charge when
completed.
•
Confirm all the valves in the system fully open, except for the EEV.
•
The initial refrigerant must be charged with 80% of the circuit volume. The charge must be
applied after the second check valve on the discharge line with the compressor OFF. This
will fill the high side of the system.
•
If the EEV is in the close position, use a liquid charging adapter to break the vacuum at the
compressor suction and discharge Rotolock service valves with 90 PSIG of liquid refrigerant.
A liquid charging adapter prevents liquid refrigerant from entering the compressor.
•
In some cases, the assistance of a refrigerant recovery machine may be necessary to add
the initial charge.
•
Care must be taken to prevent from over charging the system and from liquid entering the
compressor and diluting the oil.
•
The return air temperature to the unit being charged must be stable and must be maintained
greater than 65°F (18°C). If this is not possible due to lack of heat load, then load banks must
be used to offset the cooling load during startup.
•
Start the unit up by using the setpoint under Menu B
– Setpoints
•
When charging, if the ambient is less than 60 degrees, some refrigerant will be backed up in
the condenser coil, causing the liquid level to drop. If head pressure is below 320 psi, block
the condenser coil surface, or turn OFF the fans until pressures rises above 380 psi, while
observe the receiver sight glass.
•
Do not obtain final refrigerant reading when the variable speed compressor is running at low
speed.
•
Heat load is required when adjusting charge, use load banks to offset the cooling load.
•
Suction pressure should be equal to 33 degrees saturated temperature or greater
•
When the system is properly charged the EEV valve should be between 55% and 85% with
an indoor temperature of 70°F to 74°F.
•
See further instructions for the following options:
o
5.6.1 Air Cooled System Charging
o
Section
5.7.2 Flooded System Charging (Systems with Low Ambient Receiver Package)
o
Section
5.7.3 Water/Glycol-Cooled System