What are the different types of heat pumps?

Air-source heat pumps are the most common (see question number 1). Ground-source heat pumps use water in underground pipes as the heat source (or sink), rather than air. They are more expensive than ASHPs but are also more efficient. Ground-source heat pumps can be used for larger homes, for homes in colder climates (such as Colorado mountain areas), or for multi-family buildings or schools.

There are also “air-to-water” heat pumps, which are air-source heat pumps that transfer heat from the heat pump to water rather than to provide warm air. These systems are less common, but can be used to provide hot water for radiant heating systems.