Heat pump water heaters (HPWHs) are much more efficient than conventional electric water heaters because the electricity they use is moving heat from one place to another rather than generating heat directly. Costs will initially be higher, but HPWHs can be easily paid for in a few years of operation since efficiency is two to three times higher.
Heat pump water heaters are often combined with air heating and cooling systems, but they can stand alone as well, with the help of backup heating elements. They are available as integral units with built-in water tanks or as add-ons to conventional storage water heaters.
Works like a refrigerator, only in reverse
Instead of taking heat from inside an enclosure, a heat pump water heater pulls heat out of the air and puts it into a tank (which is why they can be great air conditioners). The cool exhaust air can be vented into the room or outside. Some extra heating may be required in cooler weather if the air is vented inside, but some systems also allow the possibility for venting inside in the summer and outside in winter. HPWHs can pull heat from the air inside or outside the house.
Since they pull heat out of air, it's understandable that HPWHs work better in warmer climates. The colder the air is, the less efficiently they work. They are also more practical when air cooling is constantly required.
A heat pump should be installed in areas that range in temperature from 40 to 90 F and have at least 1,000 cubic feet of air space surrounding them. A room with excess heat, like a furnace room, is ideal.
As an add-on to air cooling methods
For heating water with an existing geothermal heat pump system or air conditioner, you can add a small, auxiliary heat exchanger that uses hot gases from a heat pump's compressor to heat water. It's known as a desuperheater. The heated water is piped to a storage water heater's tank and, on average, can meet 20 to 40 percent of yearly hot-water demand.
Talk to an expert
You might be able to choose from differentwater heater types based on sizing and water heater efficiency priorities on your own, but since there are so many variations involved in heat pump water heaters, it's important to talk to an expert about how it will work for you. Just make sure they're experienced in dealing with these types of machines.