A heat pump is a device that uses a small amount of energy to move heat from one location to another. Heat pumps are usually used to pull heat out of the air or ground to heat a home or office building, or they can be switched into reverse to cool a building. If you know how an air conditioner works, you already know a lot about how a heat pump works, because heat pumps and air conditioners operate in very similar ways.
Heat pumps are a unique kind of heating system, because they can do the work of both a furnace and an air conditioner. Thus, there’s no need to install separate systems to heat and cool your home. Heat pumps can also work extremely efficiently, because they simply transfer heat, rather than burn fuel to create it.
Heat pumps work best in moderate climates. If you live in a moderate climate, using a heat pump instead of a furnace and air conditioner may help you save money on your utility bill. Most heat pumps are somewhat limited by the cold, however, so it is important that you learn which kind of heat pump is best for your area before installing one in your home or office building. If you install the wrong kind of heat pump, you may end up paying even more in energy costs than you do already.
Air-Source and Ground-Source Heat Pumps
As we discussed in the previous section, air-source heat pumps use a fan in an outdoor unit to bring air over refrigerant-filled coils. Two sets of these coils transfer heat indoors, where the heat is taken away from the coils to indoor by another fan, or to the hot water by circulating water flow and distributed through the house. Some air-source heat pump systems consist of a single “packaged” unit containing both sets of coils in one box. This box is then installed on the roof of a building with the ductwork extending through the wall. Larger systems for commercial buildings often are installed in this way. Home heat pumps are usually “split” systems with an outdoor and indoor component installed through the wall, or “integrative” system for heating hot water and distributing the heat through the hot water system inside the house. Depending on the type of system, there may be one or more indoor components to distribute that.