Which components are considered the main parts of an air-to-air heat pump?

The main components of an air-to-air heat pump are the compressor, evaporator, condenser, and expansion valve. The compressor is responsible for circulating refrigerant through the system and raising its pressure and temperature. The evaporator absorbs heat from the outside air, allowing refrigerant to evaporate and become a gas. This gas is then compressed further by the compressor, increasing its temperature.

The condenser is where the refrigerant releases the heat it has absorbed, allowing it to transition back into a liquid state. The expansion valve regulates the flow of refrigerant into the evaporator, controlling the cooling or heating process based on demand. Together, these components work to transfer heat from the air outside into the home during heating mode and vice versa during cooling mode, making them essential for the efficient operation of an air-to-air heat pump.

Other options mention components that play significant roles in HVAC systems but do not represent the fundamental parts that specifically define the operation of an air-to-air heat pump.