Stiebel Eltron Accelera 220E - 58 Gallon Heat Pump Water HeaterThe Accelera 220E, boasts increased efficiency, with an even higher Energy Star rating! A heat pump water heater is not a new concept. The Accelera 220E works like an air conditioner but instead of dumping the heat outdoors, it puts it into the water. The Acceleras compressor and fan consume only 1kWh of electricity to generate the heat equivalent of 3 5kWh. The efficiency of the unit goes up with increasing ambient air temperatures. This