Blue bird use the high-energy accumulator case which designed by Kanou R & D officed. Consumer paid one price get twice the value, water heater + air conditioner. According to physic of material; Expands when it is heated, shrinks when it is cooled; The compressor compresses the refrigerant and release heat and stored it in the heat storage tank. When require hot water, water run through heat exchanger in the heat storage tank. Water temperature is raised to proper level (water heater function). The compressed refrigerant flow through the evaporator, expands, absorbed heat and cool the air of the Indoor Unit (air conditioning function). Blue Bird is ideal for living room & bed room installation in apartment building and single family house. It is also suitable for hair salon, hotel suite, bath house etc.