One way to think of a heat pump is as a reversible air conditioner, which means that one device can provide both heating and cooling. Heat pumps capture heat from the outdoors and compress it. The compressed heated air is then pumped around the home or business. The heat pump doesn’t actually generate heat. The principle by which heat pumps work is the same as air conditioners. However, air conditioners cycle the opposite way, expelling heat to the outdoors, instead of drawing it in. While heat pumps are typically reversible and can function as air conditioners, not all air conditioners can be reversed to function as heat pumps.
Although heat pumps have the advantage of both cooling and heating, their functionality is limited to a moderate climate. An example of an appropriate climate for a heat pump only system would be Washington, DC. As an air conditioner, a heat pump can provide cooling air during hot temperatures. When temperatures drop below freezing though, it becomes harder for a heat pump to work as a heater. Since it functions by drawing heat from the air, it struggles to draw heat from freezing air. One solution is to add electric resistance coils to the heat pump. These coils function as a furnace and provide heat when it’s too cold to draw warmth from outdoor air.
Above freezing temperatures, heat pumps can be up to 40% more efficient than gas furnaces. Heating air requires a great deal of energy. Gas furnaces physically heat the air with a flame. However, heat pumps transition the warmth outdoors into the indoors (though compressing the air can be energy intensive). Heat pumps are more efficient than furnaces until additional electrical resistance coils need to be used to heat the air, which usually occurs around freezing temperature. At this point, the electrical or gas resistance coils are not as efficient as a gas furnace.
If a heat pump promises to meet your heating and cooling needs, there are a few options to consider. Heat pumps come in a variety of sizes, measured in tonnage. To properly size a heat pump, home and business owners should complete a heat load calculation. This calculation takes insulation, square footage and climate factors into account and then recommends a tonnage. Heat pumps are usually electric, but some resistance coils can be gas-powered, depending on your preferences. SEER, or seasonal energy efficiency rating, is another way to determine the best heat pump for a home or business. Higher ratings translate to a more efficient heat pump. With these options in mind, it’s easy to select the appropriate heat pump for your home or business.