Trane TRG-TRC004-EN manual Xqordghufrqwuroohu Vrohqrlgydoyh Ydoyh

period two

Compressor Capacity Control

notes

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In response to an increasing load, the controller sends a signal to close the solenoid valve. This closes the port that allows the pressurized refrigerant vapor to travel to the top of the unloader valve. A controlled leakage rate around the unloader valve relieves the pressure, allowing the valve to open and refrigerant vapor to once again flow to the cylinder to be compressed.

Another type of cylinder unloader uses either pressure or electrically-actuated valving mechanisms to hold open the suction valve of the piston–cylinder pair. Since the suction valve is prevented from closing, no compression occurs in that cylinder and the discharge valve does not open. Still other types of cylinder unloaders divert the compressed refrigerant vapor back to the suction side of the compressor. In contrast to the cylinder unloaders shown, these other methods expend energy in moving refrigerant vapor during both the upward and downward piston strokes within the unloaded cylinders.

20 TRG-TRC004-EN