Sterling SCW Series Chilled Water Circuit, Refrigeration Circuit, Freezestat Control

4-5 Chilled Water Circuit

If your central chilling station is equipped with the optional integral pump tank, make the process cooling water supply connection at the P1 manifold at the left side of the pump tank at the exposed connection. Bring the process cooling water return connection to the Hot well of the tank on the right side at the flanged connection.

Warm coolant (water and ethylene glycol mixture) returns from the process to the tank, then gets pumped through the evaporator where it is cooled. The coolant flows to the process and returns to repeat the cycle.

4-6 Refrigeration Circuit

•SCW Series chilling station air- and water-cooled unit refrigeration cycles differ only in the way the compressed gas is condensed to a liquid.

•Liquid refrigerant from the condenser passes through a shut-off valve into a filter/dryer.

•The refrigerant then passes through the sight glass and solenoid valves into the thermal expansion valve which regulates flow; the valve lowers pressure and boiling point. Heat from the fluid causes the refrigerant to boil off into a vapor.

•The refrigerant vapor flows through the suction line back into the compressor.

•The refrigerant gives up heat as it re-condenses to a liquid in the condenser.

4-7 Freezestat Control

The freezestat shuts down the compressor if the chilled water temperature approaches the freezing point. The chilled water pump on the system will continue to run. It is factory-set at 40°F (4ºC) or 10°F (6ºC) below the rated capacity operating temperature of 50°F (10ºC).

SCW Series Central Chilling Stations Page 29 of 77