Heat Pumps for Heating, Cooling, and Water

A heat pump moves heat from one place to another using a vapor-compression cycle—the same technology as a refrigerator but reversible. In winter, it extracts heat from outdoor air (even at temperatures below freezing) and pumps it inside. In summer, it reverses and pumps heat outside, functioning as an air conditioner. The key advantage is efficiency: for every unit of electricity consumed, a heat pump delivers 2-4 units of heat—expressed as a coefficient of performance (COP) of 2-4. A gas furnace converts one unit of gas into 0.95 units of heat at best. Modern cold-climate heat pumps maintain a COP above 2.0 even at -15°F, making them viable in virtually all US climates.