| 摘要 |
PURPOSE:To ensure the accurate operation of a low temperature operating valve by connecting the upstream side of a heat exchanger to the downstream side thereof by a bypass passage having quantitative valves on both upstream and downstream sides of the heat exchanger, and passing water to the low temperature operating valve via the heat exchanger upon operating the low-temperature operating valve. CONSTITUTION:In a gas instantaneous water boiler 1 directly connected to the service water supply, a bypass passage 20 is connected to a water flow passage at the downstream side of a heat exchanger 7 from the upstream side of a flow switch 6 provided in the water flow passage 4, to provide a quantitative closing valve 21, a branch pipe 24 extends from the substantially central part of a fin pipe 23 of the heat exchanger 7, and a low-temperature operating valve 12 is mounted thereon. When the temperature of external air reaches less than a predetermined value and the valve 12 operates, the valve 21 opens. At the time of supplying hot water where any of hot water supply plugs 9, 10 and 11 is opened, the valve 21 is closed and only the water flow passage 4 is opened. By this operation, the erroneous operation of the valve 12 due to thermal transmission is eliminated, and further freezing can be prevented because there is no part where hot water is difficult to flow through the water flow passage 4. |
