AirTap is an affordable heat-pump module that can be retrofit onto a conventional electric or gas water heater. The unit has a first-hour rating of 42.5 gallons, an efficiency of 240%, and a GAMA-tested energy factor of 2.11.
While a heat-pump water heater will save significant energy on a year-round basis, be aware that in a cold climate the net performance (water heating plus space heating) will drop in the winter.
