Expansion valves

Electronic expansion valve:

   These types of expansion valves control the flow of refrigerant entering a direct expansion evaporator. They do this in response to signal sent to them by an electronic controller. A small motor used to open and close the valve port that is called a step or stepper motor. Step motors don't rotate continuously, they are controlled by an electronic controller and rotate a fraction of a revolution for each signal sent to them by the electronic controller. The step motor is driven by a gear train, which position a pin in a port in which refrigerant flows.

Float expansion valve:

   The float valve operates by float immersed in the liquid refrigerant. Both low side float and high side float are devices used to control the flow of liquid refrigerant.

   

   The low side float valve helps maintain constant level of liquid refrigerant in the evaporator. It opens when there is no liquid in the evaporator and closes when there is liquid in the evaporator. 

    The high side float valve is located at the high pressure side of the system that maintains constant level of refrigerant in the condenser. When the compressor operates, the condensed refrigerant flows to the float chamber and opens the valve.