| 摘要 |
<p>PURPOSE:To separate an arithmetic operation result output means from an electric heater when an operational failure of a power supply calculation means is detected and connect an auxiliary temperature control means having an arithmetic operation means to the electric heater on the other hand and hence boil up the hot water. CONSTITUTION:The temperature of water or hot water in a hot water storage tank is detected with a temperature sensor 9. The power supply to an electric heater 5 is computed with an arithmetic operation means 7 based on an detection signal. A switching contact 4, which is connected to the electric heater 5 in serial, is turned on and off in conformity with the results of the arithmetic operation. This constitution allows a monitor means 18 to monitor the operation of the arithmetic operation means and to detect and operational failure, if any. If no operational failure is detected, the switching contact 4 of the output means 3 is connected to the electric heater 5 in serial with a change over means 2. On the other hand, when an operational failure is detected, the switching contact 4 of the output means 3 is separated from the electric heater while the arithmetic operation means 7 and an auxiliary temperature control means 22 having a substitute function of the output means 3 are connected to the electric heater 7 in serial.</p> |
