| 摘要 |
PURPOSE:To prevent freezing during a winter season by expelling all water from the piping and yet facilitate the priming of a circulating pump when the bath boiler is going to be used by providing a three-way valve in a water circulating passage on the sucking side of the circulating pump as well as a water drain valve in a priming water supply passage and the water circulating passage. CONSTITUTION:When the drain switch is turned on, a shutoff valve 12 is closed, a drain valve 15 is opened, and a three-way valve 6 is actuated to communicate a communicating pipe 7 with a circulating pump 4. After a certain time required to completely drain a reservoir tank 8 has elapsed, the communicating pipe side 7 of the three-way valve 6 is closed and the feed pipe side 5a opened to drain all the water in a water circulating passage 5. After the drain switch is turned off and the drain valve 15 closed, hot water is supplied to a bathtub 1 through a hot water discharge pipe 10 of a water heater 3. A supplemental heating switch is turned on and the shutoff valve 12 is opened to supply water to the reservoir tank 8 from the water heater 3 via a branch pipe 11. At the same time, the three-way valve 6 is switched to allow the flow between the communicating pipe 7 and the circulating pump 4 to supply the priming water to the circulating pump 4 from the reservoir tank 8. |
