Rinnai Corp developed what it claims is the world's first domestic water heater that combines an air-to-water heat pump and a gas water heater.
The water heater, which the company calls "hybrid water heater," will be released April 2, 2010, in Japan. Because the heater has the same air heating function as the company's "Eco Jyouzu" gas water heater, it can be used not only for heating water but also for floor heating and bathroom heating.
The hybrid water heater switches heat sources in accordance with the needed amount and temperature of water. To supply a small amount of hot water, only the heat pump is used. The heat pump and the Eco Jyouzu gas water heater are used to supply a large amount of hot water such as for a bath. And only the gas water heater is used for floor heating and bathroom heating.
The energy efficiency of the water heater was improved by 24% because heat sources can be switched, Rinnai said. Its annual CO2 emission was reduced by about 20% compared with that of the Eco Jyouzu gas water heater and by about 30% compared with that of the Eco Cute heat pump-based water heater (460L model). And the annual running cost of the hybrid water heater is about half that of the Eco Jyouzu gas water heater.
The amortization period of the hybrid water heater is about seven years. It will be available in two models. One comes with heat source equipment integrated with a water tank, and the other has heat source equipment separated from a water tank. Their prices are ¥756,000 (approx US$8,457) and 735,000 (including tax), respectively.