| 摘要 |
<p>PURPOSE:To effectively and previously prevent a water cut phenomenon by controlling the conduction of an upper side heater and a lower side heater both located in a hot water tank such that the conduction of the upper side heater has preference to that to the load side heater. CONSTITUTION:In a midnight power service time, power is first supplied to an upper heater 14 by the control of conduction by a controller 18, whereby an upper portion from the heater 14 is rapidly boiled. When hot water is used for midnight bathing, showering, etc., the amount of the hot water in a tank is correspondingly reduced. In this occassion, since the power has been supplied to the upper heater 14 based upon temperature detection by an upper temperature sensor 15, the upper portion in the tank is again boiled after the elapse of certain time into high temperature hot water. Once supply water heating by the upper heater 14 is completed, power is supplied to a lower heater 13 by the controller 18 to heat and boil water stored in the lower portion in a hot water storing tank 10. Following the boiling, the whole water in the hot water tank 10 is boiled.</p> |
