Which component rejects heat from the refrigerant to outdoor air in heating mode?

• A. Evaporator
• B. Condenser
• C. Expansion valve
• D. Compressor

Answer: (B)

In heating mode, a heat pump pumps heat from inside to outside. After the refrigerant is compressed, it becomes hot and high-pressure. The condenser, located in the outdoor unit, passes this hot refrigerant through its coil, where it releases heat to the outdoor air and changes from a high-pressure vapor to a liquid. That heat transfer to the outside air is what provides warmth to the indoor space indirectly.

The evaporator, by contrast, is inside and absorbs heat from indoor air. The expansion valve only lowers the refrigerant’s pressure before it goes to the evaporator, and the compressor’s job is to move and pressurize the refrigerant—not to reject heat to outside air.