Air Source Heat Pumps

Air-source heat pumps are year-round space-conditioning systems capable of providing heating, cooling, and domestic hot water. Their appeal lies both in that they offer heating and cooling in a single piece of equipment—which usually means a lower capital cost—and in that they provide heat at a lower cost than electric resistance heating (in some cases, lower than gas heating as well). They can be used in most commercial applications and some industrial processes, particularly those that generate waste heat.

An air-source heat pump transfers energy between the outside air and either air or water inside a building. In cooling mode, it functions just like an air conditioner, moving heat from the inside of a building to the outside; in heating mode, the refrigerant flow is reversed so it takes low-temperature heat from the outside air and mechanically concentrates it to produce high-temperature heat, which is then delivered to a building (Figure 1). Because most of the heat is simply moved (pumped) from the outdoor air to the indoors, the amount of electricity required to deliver it is typically less than would be required from electric resistance heat.