HO-82-01-3 -- Heat Pump Water Heaters with a Comparison to Solar Domestic Water Heaters PDF

A heat pump water heater (HPWH) is a conservation water heating system for new and retrofit residential and commercial applications. There are two generic types of HPWHs: (1) a stand-alone appliance-type heat pump unit plumbed to a conventional water tank, and (2) an integral heat pump/water tank unit with the heat pump installed on top of the tank. Both types are installed independently of the space conditioning equipment. In each case, the heat pump draws in air, extracts heat from it, and uses this to beat the tank water. A byproduct of the system is cool, dehumidified air discharge.

Depending on the season of the year, the geographical area, and the building location of the HPWH, the overall system efficiency is increased or decreased by cooling effects on the space-conditioning load. Since HPWHs do not operate below 70C (45 F) and have no freeze protection, the preferred installation location is an unconditioned building space, such as a basement, crawl space, or utility room . HPWIls have become commercially available in the past year and cost under $1,000 installed . At least seven manufacturers plan to market HPWHs within the next 6 to 12 months.