HOT WATER HEATING APPLIANCE

PURPOSE:To enable execution of filling water at the time of construction while preventing leakage at the time of injection of heating water, without using a pressurizing pump, and also to enable simple injection of the water into a hot water tank even in the case when a hot water heating appliance is of a type of suspension from the ceiling, for instance, and a space between an injection port of a water injection tank and the surface of the ceiling is small. CONSTITUTION:In a hot water heating appliance 1 which is equipped with a hot water circuit 3 constructed by connecting a hot water tank 2 having in the upper part an opening to which a cap 13 with a pressure regulating valve is fitted, a circulating pump 4 and a heat exchanger 6 sequentially and wherein hot water in this hot water circuit 3 is supplied in circulation to a heating load 9, an water injection tank 22 fitted airtightly to the opening in the upper part of the hot water tank 2 is provided and this water injection tank 22 is so constructed that it can be extended and contracted in the length.