A 4-Way Reversing Valve has four ports for tube connections. Three of these ports are on one side, and the fourth is on the opposite side.

The three copper tube ports have a larger diameter than the single port on the opposite side. The middle of the three large ports is permanently connected to the suction line, and the single small port is permanently connected to the pressure line.

As the two remaining ports can be connected to the suction line or the pressure line depending on the valve position, because of pressure drops they have the same dimensions as the permanent suction line port.

A 4-Way Reversing Valve also has a solenoid pilot valve with a coil, which changes the direction of refrigerant ow when it is energised.

There are also small pilot lines running from the small valve port to the solenoid pilot valve and back to the middle large port.

4-Way Reversing Valve4-Way Reversing Valve used in reversible refrigeration systems
A 4-Way Reversing Valve has four ports for tube connections. Three of these ports are on one side, and the fourth is on the opposite side. The three copper tube ports have a larger diameter than the single port on the opposite side. The middle of the three large ports...