What component is primarily responsible for changing the direction of refrigerant flow in a heat pump?

The component responsible for changing the direction of refrigerant flow in a heat pump is the reversing valve. This valve allows the system to either absorb heat from the outside air (in heating mode) or release heat to the outside air (in cooling mode), effectively reversing the flow of refrigerant.

In heating mode, the reversing valve directs the refrigerant to the indoor coil to absorb heat, while in cooling mode, it directs the refrigerant to the outdoor coil to release heat. This function is essential for the heat pump's operation, as it enables the unit to efficiently provide both heating and cooling, depending on the needs of the environment.

The other components, while important to the overall operation of the heat pump, do not serve the function of changing the refrigerant flow direction. The compressor is responsible for circulating the refrigerant and increasing its pressure, the evaporator facilitates heat absorption by the refrigerant, and the expansion valve controls the flow and pressure of refrigerant entering the evaporator.