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HVACR317 - Refrigeration. Solenoid Valve Pump Down Systems. Solenoid Valves. A Solenoid Valves is a mechanical/electrical valve. The mechanical part is in the refrigeration or water line. The electrical portion is a coil that is attached to the top of the valve. Solenoid Valve Examples.
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HVACR317 - Refrigeration Solenoid Valve Pump Down Systems
Solenoid Valves • A Solenoid Valves is a mechanical/electrical valve. • The mechanical part is in the refrigeration or water line. • The electrical portion is a coil that is attached to the top of the valve.
Solenoid Valves • The valve in the closed position is not powered, and the flow of liquid is being blocked by the plunger in the DOWN position. • In the closed position, the coil does not produce any magnetic field as it is not powered.
Solenoid Valve - Open • The valve opens when the coil is powered. • The coil generates a magnetic field and pulls the plunger into the up position. • This allows fluid flow through the central passage of the valve.
Solenoid Valves • In refrigeration, solenoid valves mainly have two uses: • Hot Gas By-Pass Defrost • Pump Down Systems
Pump Down System • The solenoid in the pump down system is used in the liquid line prior to the metering device and after the receiver. • The solenoid is in the normally closed position. • When the thermostat calls for cooling, the solenoid opens.
Pump Down System • This releases refrigerant into the liquid line and raises the pressure of the system. • A pressure switch senses this pressure increase and turns on the compressor. • When the call for cooling is complete, the thermostat de-energizes the solenoid.
Pump Down System • The solenoid closes and blocks the flow of refrigerant into the liquid line. • The refrigerant gets pumped into the receiver, which is mounted after the condenser coil. • Once the refrigerant is pumped down into the receiver, the pressure on the system drops.
Pump Down System • Once the pressure has dropped to a pre-determined point, the pressure switch opens and shuts off the compressor.