What is the application of a Hot Gas By-Pass valve on an evaporator?
If the evaporator pressure (temperature) falls below 0 C due to lack of duty, an ice bank could build up on the coil reducing the duty and therefore creating even more ice. This can be prevented by the introduction of discharge gas into the pipe between the expansion valve and distributor. The set point of the outlet pressure regulator would be the lowest allowable pressure. When the pressure falls below set point the valve opens and injects hot gas into the evaporator, as the pressure rises the valve gradually closes. This valve should be fitted with a solenoid for electric shut off when used on pump down systems.
