| 摘要 |
PROBLEM TO BE SOLVED: To solve such problems that in a control of determining completion of replacement of water in a hot water storage tank by temperature changes in the hot water storage tank, it becomes difficult to detect a difference between the temperature of hot water in the hot water storage tank and the temperature of water supplied from a water supply pipe, when the temperature of the hot water remaining in the hot water storage tank is low or the temperature of tap water is high in summer time, and therefore, a replacement operation is terminated before the replacement of water in the hot water storage tank is completed.SOLUTION: When starting a replacement operation of the hot water in a hot water storage tank 10 and when the temperature detected by a temperature detecting means 40 is equal to or lower than a first threshold, the replacement operation of the hot water in the hot water storage tank 10 is carried out based on a valve opening time of a drain valve 34, and also, when starting the replacement operation of the hot water in the hot water storage tank 10 and when the temperature detected by the temperature detecting means 40 is equal to or higher than the first threshold, the replacement operation of the hot water in the hot water storage tank 10 is carried out based on temperatures detected by a plurality of temperature detecting means 40, 42. |
