HEAT PUMP WATER HEATERS
To move the heat, heat pumps work like a refrigerator in reverse. While a refrigerator pulls heat from inside a box and dumps it into the surrounding room, a stand-alone air-source heat pump water heater pulls heat from the surrounding air and dumps it—at a higher temperature—into a tank to heat water.
Heat pump water heaters require installation in locations that remain in the 20º–120ºF range year-round and provide at least 1,000 cubic feet of air space around the water heater. Install them in a space with excess heat, such as a furnace room. They tend to cool the spaces they are in.
Heat pump water heaters have higher initial costs than conventional storage water heaters. However, they have lower operating costs, which can offset their higher purchase and installation prices.