Operating manual – DualPAC with reciprocating compressors
0012201 en 2021.04
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8.2
Control description - DualPAC
Start-up
Cold side control
The ChillPAC UniSAB control regulates according to the
Water temperature out on evaporator
.
When the temperature gets outside range, UniSAB III will initiate a start request for the ChillPAC.
The ChillPAC is not allowed to start until the HeatPAC is running, but it initiates that the setpoint
for suction pressure in the HeatPAC UniSAB III is changed to setpoint 2 (normally 10°C) and this
will start the HeatPAC. When the HeatPAC is running, it allows the ChillPAC to start.
When start-up is complete, the HeatPAC suction setpoint will change back to setpoint 1 (inter-
mediate pressure according to COMP1).
Hot side control
The HeatPAC UniSAB control regulates according to the
Water temperature out on condenser
.
When the temperature gets outside range, UniSAB III will initiate start-up of the HeatPAC. When
the HeatPAC is running, the intermediate pressure will drop, and this will initiate start-up of the
ChillPAC.
Operation
Cold side control
ChillPAC is controlled by the
water temperature out on evaporator
. When the temperature gets
outside range, the compressor will regulate capacity up or down. The capacity mode should be
set to ‘speed’ in order to regulate most fluently.
HeatPAC is controlled by intermediate pressure (suction pressure). When the pressure gets out-
side range, the compressor will regulate capacity up or down. Capacity mode should be set to
‘speed’ in order to regulate most fluently.
Hot side control
ChillPAC is controlled by intermediate pressure (discharge pressure). When the pressure gets
outside range, the compressor will regulate capacity up or down. The capacity mode should be
set to ‘speed’ in order to regulate most fluently.
HeatPAC is controlled by the
water temperature out on condenser
. When the temperature gets
outside range, it will cause the compressor to regulate capacity up or down. The capacity mode
should be set to ‘speed’ in order to regulate most fluently.
Shutdown
Cold side control
Lower the setpoint for
Water temperature out on evaporator
until the ChillPAC regulates down in
capacity and stops.
The resulting low intermediate pressure will make the HeatPAC regulate down and stop as well.
Hot side control
Increase the setpoint for
Water temperature out on condenser
until the HeatPAC regulates down
in capacity and stops.
The resulting high intermediate pressure will make the ChillPAC regulate down and stop.
