| 摘要 |
PURPOSE:To make it possible to immediately supply hot water through a water tap when the water tap is closed and opened after a predetermined time by providing bypass channels on the inlet and outlet sides of a water heating heat exchanger and adjusting combustion by a second solenoid valve. CONSTITUTION:When a water tap 1 is closed, a first water flow switch 2 is turned OFF. Therefore, a first water solenoid valve 12 is turned OFF by a combustion control device 11 and, at the time, a second water solenoid valve 13 and a pump 14 provided in a bypass channel 16 are turned ON. By the turning ON of the pump 14, a second water flow switch 15 is turned ON. This signal is input to the combustion control device 11 and a second solenoid valve 17 is closed and the combustion of a burner 8 becomes a lowest ability combustion and is continued for approximately 7min. Through the bypass channel 16 including a water heating heat exchanger 4 water is circulated by means of the pump 14 and is continuously heated by the lowest combustion ability burner 8. When the water tap 1 is reopened, hot water which has been circulated through the bypass channel and warmed is immediately supplied through the water tap 1.
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