| 摘要 |
<p>PURPOSE:To control the energizing of an electric heater by a method wherein the energizing time Tn is calculated reversely from the state time to obtain the starting time of heating an electric heater. CONSTITUTION:The temperature of hot water in a hot water storage tank 2 is maintained at a required temperature (to) (normally 80-85 deg.C). When fresh water is fed to replenish the hot water decreasing for use, the water having a temperature (ti) lower than the temperature (to) is moved into the bottom side of the hot water tank 2. In this type of the hot water heater 1 making most of the supply of midnight power granted an advantage in the power rate, it is important that all the water in the tank be heated to the temperature (to) by the stated time such as 07:00 that the midnight power rate is expired. For this reason, the freshly supplied water is required to be heated to raise its temperature (ti) to (to). Therefore, the amount of heat required for such heating is calculated and, on this basis, the time Tn of current application to an electric heater 2 is obtained and the current application time Tn is calculated reversely from the midnight power rate expiration time to obtain the starting time of the current application. In this way an efficient use of the midnight power is permitted.</p> |
