PURPOSE: To prevent generation of boiling sound from a pipe for room heating in case hot-water supplying operation is effected and save energy by a method wherein a circulating pump is provided at a position capable of circulating hot-water in a hot-water path for room heating between a bypass path while the circulating pump is operated when the temperature of supplying hot-water is higher than a predetermined value.
CONSTITUTION: In case of hot-water supplying operation, the set temperature of a temperature setter 15 and the outlet hot-water temperature (t) of a supplying hot-water temperature sensor 16 are detected when a water flow detecting switch 12 for the supplying hot-water has detected the flow of water and a micro-computer 11 determines the amount of combustion to output to a burner 8. Next, the outlet hot-water temperature (t) is decided whether it is higher than a predetermined temperature (tp) or not and when (t) is higher than (tp), the circulating pump 5 is operated. When the circulating pump 5 is operated, the hot-water in the pipe 3 for room heating circulates through the bypass path 6 and water flows in the pipe 3, therefore, heat transmitting coefficient for a hot-water supplying pipe 2 is increased and the temperature rise in the pipe 3 for room heating may be suppressed.
SAEKI IKUHO
KURAMOTO SHINJI
