An Affordable Heat-Pump Water-Heater Retrofit

UPDATE November 17, 2022: This product is no longer available. Thank you, Sandra Lester, for pointing this out.

The engineers at AirGenerate (previously Beyond Pollution) appear to have done something remarkable: create an affordable, effective, heat-pump water heater that can be retrofit onto a conventional gas or electric water heater, more than doubling the energy performance compared with a standard electric water heater. The AirTap A7 water heater has a rated output of 7,000 Btu/hour (7.4 MJ/hour), a first-hour rating of 42.5 gallons (160 l), a maximum water temperature of 135°F (57°C), an efficiency of 240% (coefficient of performance of 2.4), and an energy factor of 2.11. (Energy factor is a standardized measure of performance of water heaters; the higher the number, the better.) All this is in a unit that measures only 18" wide by 14" deep by 14" high (460 x 360 x 360 mm), weighs only 48 pounds (22 kg), and sits on top of a standard water heater. The list price is $499. The energy factor and first-hour rating of the AirTap are certified by GAMA (previously the Gas Appliance Manufacturers Association and now a broader association of appliance and equipment manufacturers).