What is a Heat Pump Water Heater?

A heat pump water heater is a highly efficient electric unit that pulls heat from the surrounding air to heat your water. Available in both conventional storage tank and tankless styles, it doesn't use electricity to power a heating element, but to move the heat around. It transfers heat rather than using fuel to create it.

Basically, a heat pump water heater works like a refrigerator, but in reverse. Like a refrigerator, it uses a condenser, compressor and evaporator to pull heat out of the air in one location and send it somewhere else. Controlling changes in pressure causes a heat-transfer liquid to expand (drawing heat from the air) and contract (generating heat). But while the refrigerator dissipates heat as a by-product, a heat pump water heater sends it to a water storage tank or tankless system's heat exchanger. A typical residential model can raise the temperature of fifteen gallons of water by 80°F in one hour.

Heat pump water heaters come as stand-alone units, or as combination heating, air conditioning and water heating systems. Combination systems pull heat from outdoor air or the ground in winter and from indoor air in summer. If your home is already heated and cooled by a heat pump, you can add an auxiliary heat exchanger called a desuperheater. This small unit utilizes the heat from your heat pump's compressor to heat water.

Stand-alone heat pump water heaters can have traditional storage tanks or be connected to the heat exchanger of a tankless system. They can be integral or separate units, and can vent cool exhaust air into the room or outdoors. They require a warm environment to operate, so must be installed in a location where the temperature doesn't drop below about 40°F. They will work in outdoor air in very warm climates, or in a furnace or utility room in colder areas. A heat pump water heater will cool and dehumidify whatever space it's in, year round, so keep that in mind when you choose where to locate it. Most models require a minimum of one thousand cubic feet of air space.

Because heat pump water heaters don't use fuel to heat the water, they only use about a third as much electricity as a regular electric model. The U.S. Department of Energy estimates that heat pump water heaters can be two to three times more energy efficient than conventional electric water heaters. They have a higher purchase price than other electric models and can be more expensive to install, but much greater efficiency over their lifespan more than offsets their initial cost.

By using electricity to move heat instead of create it, a heat pump water heater uses much less energy and reduces your hot water costs by up to sixty percent. Highly efficient and economical, a heat pump water heater is a very smart buy!