| 摘要 |
PROBLEM TO BE SOLVED: To prevent hot-temperature water from running due to rise in initial water temperature at the time of start of hot water supplying operation, by providing the first and second burner groups which exclusively heat the first and second flow paths respectively, and by permitting the combustion of the burners which are adjacent to each other, only when the capacity of burning is required of either one burner group. SOLUTION: A burner unit 1 is divided into a hot water supplying burner 1A, which is the first burner group and a space-heating burner 1B which is the second burner group. A hot water supplying pipe 5 which is the first flow path and a space-heating pipe 8 which is the second flow path are provided in parallel to the burner unit 1, penetrating through a heat transfer fin 4 across the flow of hot-temperature gas in the downstream side of hot-temperature gas. Moreover, the hot water supplying pipe 5 is heated by a plurality of hot water supplying burners 1A, and the space-heating pipe 8 is heated by a plurality of space-heating burners 1B. The hot water supplying pipe 5 and the space-heating pipe 8 are provided in parallel with the arrangement of the burners 1, and the switching of the number of the burning burners 1 is done by a solenoid valve 14. The amount of combustion is controlled by a proportional valve 3.
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