The most common type of heat pump used is the _____ heat pump?

The most common type of heat pump used is the air-to-air heat pump. This type operates by transferring heat between the air inside a building and the air outside. Air-to-air heat pumps are popular due to their relatively lower installation costs and simpler installation processes compared to other types of heat pumps, like geothermal or ground source systems which require more extensive ground work and can be more expensive to install.

Air-to-air heat pumps are also versatile, providing both heating and cooling functions depending on the season. They work efficiently in moderate climates and are suitable for residential applications, contributing to their widespread adoption. The technology has advanced over the years, improving their performance even in colder temperatures. Thus, their combination of efficiency, cost-effectiveness, and ease of use has made them the predominant choice for many homeowners and commercial buildings.