How is the movement of the piston in the reversing valve achieved?

The movement of the piston in the reversing valve is primarily achieved by bleeding pressure from one side of the piston. The reversing valve is a critical component in heat pumps, as it allows the system to switch between heating and cooling modes by altering the direction of the refrigerant flow. By controlling the pressure differentials on the two sides of the piston within the valve, the system can move the piston to the desired position.

When pressure is bled from one side, it creates an imbalance that pushes the piston toward the area of higher pressure. This movement enables the valve to either switch the direction of refrigerant flow — reversing the system from cooling to heating or vice versa — or maintain the current flow direction as needed.

This understanding is essential because other methods such as using electrical currents or mechanical linkages involve additional complexity and are not utilized for the specific function of the reversing valve's piston movement. The operation of the fan motor doesn't directly influence the reversing valve piston, making it irrelevant to the question at hand.