More and more homeowners in Georgia are switching to heat pumps. They are about 50% more efficient than electric heating systems like furnaces, according to the U.S. Department of Energy (DOE). Heat pumps, of course, can cool the homes in which they are used as well. You can use a heat pump to warm your home during the winter, and you can use it to cool your home during the summer.

Heat pumps contain valves, such as an expansion valve and a reversing valve. Like all valves, they both control the flow of fluid. Expansion and reversing valves, however, serve different purposes in a heat pump.

Overview of Expansion Valves

Expansion valves are small devices that are designed to relieve pressure from the refrigerant in a heating, ventilation and cooling system (HVAC). They are commonly used in split-system air conditioning systems and heat pumps.

Air conditioning systems and heat pumps rely on refrigerant to transfer heat. Between the condenser unit and the evaporator coil is an expansion valve. The expansion valve will lower the pressure of the refrigerant, thereby causing the refrigerant to cool. When this occurs, the refrigerant will expand while changing from a liquid to gas state.

Overview of Reversing Valves

Reversing valves are refrigerant-regulating devices that are designed to change the direction in which the refrigerant travels. They are exclusive to heat pumps. While air conditioning systems have an expansion valve, they don’t have a reversing valve.

The reversing valve in a heat pump will change the refrigerant’s direction. Heat pumps feature an indoor coil and an outdoor coil. While in cooling mode, refrigerant will absorb heat at the indoor coil. From there, refrigerant will travel to the outdoor coil to release the heat. While in heating mode, conversely, refrigerant will absorb heat at the outdoor coil and transfer it to the indoor coil. The reversing valve’s job is to change the direction of the refrigerant so that the heat pump can perform the appropriate climate-controlling action.

Differences Between Expansion Valves and Reversing Valves

Expansion valves and reversing valves aren’t the same. The expansion valve in a heat pump will relieve pressure from the refrigerant. As the pressure of the refrigerant drops, so will the temperature of the refrigerant. The newly cooled, gas refrigerant can then absorb heat at the indoor coil.

Reversing valves don’t affect the pressure or temperature of the refrigerant. Rather, they only affect the direction in which the refrigerant travels. Heat pumps require a reversing valve so that they can both cool and warm the homes in which they are used. The reversing valve will change the direction of the refrigerant when the heat pump switches from cooling to heating mode or vice versa.