| 摘要 |
PROBLEM TO BE SOLVED: To prevent freezing and explosion of a pipeline in winter by preheating-circulating, in a hot water supply system including a preheating-circulating system for heating water so as to minimize the time to reach a temperature set by a user.SOLUTION: A closed path is disposed between a first node 41 and a second node 42 to preheat water in a water tank 22 and a pipeline, when warm water is not supplied to an outlet port 32. A pump 28 is operation-controlled on the basis of whether warm water is to be used or not. The water is circulated in the closed path when the warm water is not supplied to the outlet port 32. The pump is controlled not to operate when the warm water is supplied to the outlet port 32. The pump 28 is controlled to produce a pressure for circulating the water between the first node 41 and the second node 42, only when the warm water is not supplied to the outlet port 32. |
