What is a staging valve and check valve?

The check valve is considered as a valve that serves as a diode in the field of electrical engineering.

 In order to prevent reverse flow of refrigerant, refrigerant flows in only one direction.



 For example, the check valve is installed in the path between the compressor and the condenser

 Because of the high pressure on the condenser side, the refrigerant must not flow back into the compressor again.



 Nevertheless, if the pressure on the condenser side is too high, the check valve will not deliver the refrigerant,

 I will give a plosive sound. To solve this problem, an additional valve called a staging valve is installed.


 The staging valve is installed between the check valve and the condenser.

 So

     ↙←←←←←←←←←↖ 

    ↓                                     ↑
Compressor → Check valve → Staging valve → Condenser



In this order. The staging valve extracts refrigerant from the condenser side and transfers it back to the compressor discharge side The pressure on the compressor side can be increased and the pressure on the condenser side can be lowered.