| 摘要 |
<p>PURPOSE:To reduce the quantity of remaining hot water and to minimize the maintenance cost by a method wherein a supply of water to the electrical water heater is started in such a manner that the required power supply time calculated with respect to a predetermined quantity of hot water to be used ends at the time of termination of a midnight power supply. CONSTITUTION:The control device for the electrical water heater is provided with a hot water quantity setting means 9 adopted to predetermine the required quantity of hot water to be stored in a hot water storage tank 1, a temperature detecting means 6 for detecting the temperature of feed water and the heating temperature for the feed water, a power supply time operating means 10 for calculating the required power supply time for a heat generating body 2 from the required calorific value of hot water calculated by a calorific value operating means 9 on the bases of the set quantity of hot water and the detected temperatures obtained by the temperature detecting means 6, a power supply start control means 11 for starting the supply of power to the heat generating body on the midway of a midnight power supply time zone so that the required power supply time ends at the termination of the midnight power supply time and a power supply stop control means 13 for stopping the supply of power to the heat generating body when the feed water heating temperature obtained by the hot water temperature operating means 12 on the basis of the calorific value of hot water is reached, whereby when the user determines the required quantity of hot water, the midnight power is supplied in the latter half of the midnight power supply time zone and the maintenance cost is therefore minimized.</p> |
