PURPOSE: To enable both hot-water supply and room heating to be conducted efficiently by a method wherein a heating circuit is provided with a by-pass in parallel to a heat exchanger which is inserted in a hot-water storage tank for supplying hot water, and a heat transmitting medium is selectively fed to the heat exchanger and the by-pass by a change-over means.
CONSTITUTION: The heating circuit 8 is provided with the first heat exchanger 13 which heats the transmitting medium by a heat source 12 for heating, and the second heat exchanger 14 which heats the medium by the hot water contained in the hot-water storage tank 3. The heating circuit 8 is also provided with the by-pass 15 in parallel to the second heat exchanger 14 and with the changer-over means 16 which changes over the passage of the heat transmitting medium from the heat exchanger 14 to the by-pass 15 and vice varsa. In cases where weaker heating suffices, when the change-over means 16 is changed over to the by-pass 15 side, heat loss due to radiation from the sendo heat exchanger 14 is prevented even if the hot water in the tank 3 is at a low temperature. At the time of supplying hot water, the heat loss due to radiation from the second heat exchanger 14 and the lowering of the hot-water supplying capability due to the absorption of heat by the second heat exchanger can be prevented by changing over the means 16 to the by-pass 15 side.
KUMAZAWA HIROAKI
HOTSUTA SUSUMU
TOHO GAS KK