Heat pumps transfer the warmth in air outdoors inside a home by using electricity. Almost all heat pumps can also be reversed to function similarly to an air conditioner by transferring indoor heat outside.
When air is compressed, it heats up; when decompressed, it cools down. This principle is used in air conditioners and refrigerators. Air is collected and compressed. Once its temperature drops to room temperature or lower, it is expanded, and the resulting air is colder. For these systems to work, the warm air has to be removed from the system. Air conditioners and heat pumps vent this air outside, while refrigerators release it into the room.
Heat pumps, when in heating mode, reverse this process. Air from outside the home is collected, and the warm, compressed air is used to generate heat, which is then spread through the home through ductwork or other systems. By reversing this process, the heat pump functions as an air conditioner.
Temperate air, when compressed, is warmer than compressed cold air. As a result, heat pumps are more efficient when the air outside is warmer. Because of this, heat pumps are typically not used in areas where frigid temperatures are common. However, their efficiency and versatility make them a popular choice for homeowners who need both heating and cooling.