SystemAir SysAer SR55 - Compressor Control; Compressor Rotation

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0%50%100%
0% 50% 100%
C2
C1
C2
C1
Dead zone / 2
Room Temp.
Summer
Setpoint
Winter
Setpoint
Differential Differential
0%25%50%75%100%
0% 25% 50% 75% 100%
C4
C3
C2
C1
C1
C2
C3
C4
Dead zone / 2
Room Temp.
Summer
Setpoint
Winter
Setpoint
Differential Differential
9SysAer
Operation with 2 Compressors (1/2 circuit) with proportional (P) regulation
Operation with 4 Compressors (2 circuits) with proportional (P) regulation
The compressors rotation is managed according to the circuits (in the case of a 2-circuits conguration) and
the compressors status.
The circuits and the compressors of each circuit rotation follows FIFO (First In First Out) logic, i.e. the rst
circuit to switch ON will be the rst to switch OFF and the rst compressor of one circuit to switch ON will
be the rst to switch OFF.
When a compressor is requested to start, the following conditions are observed:
The rst circuit to stop will be the rst to start.
In the selected circuit, the compressor that has been OFF for a longer time will be the rst one to switch ON.
The rst compressor to switch ON is the rst one to switch OFF.
A compressor will switch ON again, not before all the other compressors have started.
In standard operation, Summer Setpoint = 24°C, Summer Differential = 2°C, Winter Setpoint = 21°C, Winter
Differential = 2°C.
3.3. COMPRESSOR CONTROL
3.3.1. COMPRESSOR ROTATION
The number of compressors and circuits depends on unit conguration.
Compressors ON/ OFF is controlled by the room air temperature (RAT).
The compressors will not work as long as they are locked in the Service menu (P1 and P2).