CHILLER CONTROL PARAMETERS

CHILLER CONTROL PARAMETERS

1.Chilled Water Supply Temperature (CHW Supply Temp)

⇒ Setpoint usually 6–7°C. 

⇒ Maintained by controlling compressor operation and refrigerant flow. 

⇒ Impacts building cooling efficiency directly.

2.Chilled Water Return Temperature (CHW Return Temp) 

⇒ Normally around 12–14°C from building side. 

⇒ Indicates cooling load — higher return temp = higher demand.

3.Delta T (Temp Difference) 

⇒ CHW Return – CHW Supply. Ideal: 6–8°C. 

⇒ Lower delta T = flow too high or load too low. 

⇒ Important for energy optimization and sizing.

4.Chilled Water Flow Rate 

⇒ Must meet minimum flow for evaporator (to avoid freezing). 

⇒ Controlled by VFD pumps, 2-way valves, or bypass lines. 

⇒ Flow switch protects evaporator from dry run.

5.Evaporator Pressure & Temperature 

⇒ Used to monitor refrigerant evaporation process. 

⇒ Sudden drop = low refrigerant or blocked flow. 

⇒ Used to trip chiller on low pressure.

6.Condenser Water Temperature (In/Out) (Water-Cooled only) 

⇒ Typical: 30–37°C in / 35–42°C out. 

⇒ Affects condenser pressure and overall chiller efficiency. 

⇒ High condenser temp = poor cooling tower performance.

7.Refrigerant Pressure – Low Side & High Side 

⇒ Low side (evaporator): for cooling. 

⇒ High side (condenser): for heat rejection. 

⇒ Helps detect abnormal conditions like: 

• Low refrigerant charge  
• Blockage  
• Overheating

8.Compressor Current (Amps) 

⇒ Shows actual compressor load. 

⇒ High current = heavy load or high head pressure. 

⇒ Used for overload protection and energy monitoring.

9.Alarms & Trips 

⇒ Low CHW flow 

⇒ High condenser pressure 

⇒ Low refrigerant pressure 

⇒ Compressor overload 

⇒ Sensor failure

10.BMS/PLC Integration Points 

⇒ Start/Stop command 

⇒ CHW temp setpoint override 

⇒ Status feedback (Running/Fault) 

⇒ Real-time monitoring of: Temps, Pressures, Flow, Alarms.