Condenser Freeze Prevention

This control algorithm helps prevent condenser tube freeze-up by energizing the condenser pump relay. If the pump is controlled by the PIC, starting the pump will help prevent the water in the condenser from freezing. Condenser freeze prevention can occur whenever the machine is not running except when it is either actively in pumpdown or in Pumpdown Lockout with the freeze prevention disabled (refer to Control Test table, Pumpdown/Terminate Lockout tables).

When the CONDENSER REFRIG TEMP is less than or equal to the CONDENSER FREEZE POINT, or the ENTERING CONDENSER WATER temperature is less than or equal to the CONDENSER FREEZE POINT, then the CONDENSER WATER PUMP shall be energized until the CONDENSER REFRIG TEMP is greater than the CONDENSER FREEZE POINT plus 5° F (2.7° C). An alarm will be generated if the machine is in PUMPDOWN mode and the pump is energized. An alert will be generated if the machine is not in PUMPDOWN mode and the pump is energized. If in recycle shutdown, the mode shall transition to a non-recycle shutdown.

Tower-Fan Relay

Low condenser water temperature can cause the chiller to shut down on low refrigerant temperature. The tower fan relay, located in the starter, is controlled by the PIC to energize and deenergize as the pressure differential between cooler and condenser vessels changes in order to prevent low condenser water temperature and to maximize machine efficiency. The tower-fan

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Carrier PC211 specifications Condenser Freeze Prevention, Tower-Fan Relay