Chiller configuration

In the standard configuration, the chiller plant consists of multiple parallel condenser pumps which are controlled by the sequencer module “SQA_ChillerSeq“. The parallel chilled water pumps are controlled by another sequencer module “SQA_ChillerSeq“. The chiller output module controls the condenser water valve, the chilled water valve and the chiller start-stop. Because there is no direct relation between a chiller and a condenser pump/chilled water pump, the chiller module calculates the number of condenser pumps and the number of chilled water pumps and commands it via communication signal inputs/outputs “ReqCdPump” and “ReqChwPump”.

The respective condenser pump sequencer module and the chilled water sequencer module starts the requested number of pumps and displays the number of operating pumps via the inputs/outputs “OperCdPumps” and “OperChwPumps”, see next figure.

Fig. 3.   Multiple parallel pumps

If the chiller is only equipped with a condenser pump, a chilled water pump and a chiller start-stop command (that is, no condenser valve and/or chilled water valve), then the chiller output macro “CHA_ChillerCmd“ can still be used. The condenser pump and chilled water pump can be controlled directly via the outputs “CdValvePmpCmd” and “ChWatValvePmpCmd“.

If the chiller is equipped with a condenser pump, a condenser valve, a chilled water pump and a chilled water valve, then additional programming is required to control each output.

When using a CHA_ChillerCmd macro standalone without status inputs, it is recommended to connect the outputs “ReqCdPump” and “ReqChwPump” to the respective inputs, to be safe of trouble with alarm behaviour caused by parameter adjustment, see next figure.

Fig. 4.   standalone