Patent ID: 8056825

Claim:
A hot water storage tank which is heated by a circulated refrigerant of a heat pump to produce hot water therein, the hot water storage tank comprising a heat exchanger provided in the hot water storage tank, the heat exchanger having a wall, wherein: the wall includes a cylindrical wall body, a top cover and a bottom cover, the cylindrical wall body includes two metal plates having an inner metal plate and an outer metal plate, the outer metal plate includes an inlet hole and an outlet hole for passing refrigerant therethrough, peripheral edges of the inner metal plate and the outer metal plate are seam-welded, in an inside portion other than the peripheral edges of the inner metal plate and the outer metal plate, the inner metal and the outer metal are partially secured by welding, portions to form secured portions, non-secured portions in the inside portion, which are portions other than the secured portions, swell outwardly, the swelling non-secured portion and the sealed peripheral edges constitute a closed refrigerant passage between the inlet hole and the outlet hole, the heating tank further comprises a cylindrical partition plate concentrically arranged with a space from an inner side of the tank main body, a height of the cylindrical partition plate is greater than a height of the cylindrical body, the hot water storage tank further comprises a cylindrical tank main body, the heat exchanger has a cylindrical shape, and is arranged concentrically with the tank main body, and a plurality of heat exchangers are concentrically arranged.