22 WGS 130A to 190A OM WGS-5
Next off?
Stage down now?
Pumpdown circuit
Yes
Yes
No
No
Run Compressor
When in the Run state, the compressor will load/unload as needed to satisfy the
load. The compressor will also load/unload to load balance with the other
compressor if it is running and not in a limited condition. However, it cannot load up
until the discharge superheat has been over 22 F for at least 30 seconds. After this,
the circuit status will be
Run:Normal
.
The EXV will operate in either Pressure Control or Superheat Control. In Pressure
Control, the evaporator pressure is controlled to a target pressure, which is adjusted
based on LWT and discharge superheat. In Superheat Control, the suction
superheat is controlled to a target that varies with discharge superheat.
If unit is aircooled, fans will be staged on and off to control the condenser pressure.
The condenser pressure is controlled to a target that is based on evaporator
pressure, with the target getting higher as the evaporator pressure gets higher.
If this compressor has the most run hours or the other compressor is already off,
then this compressor will be designated as the next one off.
If less cooling capacity is needed, the compressor designated as next off can shut
down. This condition may arise when either the LWT has dropped far enough below
the active set point or both circuits are running at a low capacity.
When the circuit does a normal shutdown, a pumpdown is performed. The EXV is
closed while the compressor continues to run. As soon as the pumpdown is
initiated, the compressor is unloaded to the minimum. The condenser fans
continue to control normally during this process. The circuit status during this time
is
Run:Pumpdown
.
After the evaporator pressure drops below the pumpdown pressure or enough time
has passed, the compressor and fans are shut off to end the pumpdown process.
The circuit status will normally be
Off:Cycle Timers
at this time.
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