| 摘要 |
PURPOSE:To save power by a method wherein the upper part of water in a hot water tank is kept at a high temperature in a midnight power supply time zone so as to meet an unexpected need for hot water irrespective of the quantity of hot water used on the previous day and the temperature of the hot water is selectively determined in response to the variation of the temperature of the city water. CONSTITUTION:When the temperature of the city water is high, switches 33 and 33' are turned on (a) whereupon a relay 30 is not energized but a relay 32 is energized through high and low temperature thermostats 27 and 28 with the result that a contact 321 is closed to energize only a main heater 2 provided in the lower part of the hot water tank. Further, when the switches 33 and 33' are turned on (b), the relay 31 closes a contact 311 so that only an auxiliary heater 3 provided in the upper part of the hot water tank is energized. Thus, when the upper part of the water in the hot water tank is heated to a high temperature, an upper thermostat 25 is opened, the contact 301 is turned on B side and the relay 32 closes a contact 321 to thereby energize the main heater only. On the other hand, when the temperature of the city water is low, the switches 33 and 33' are turned on (c) to perform the same manner of heating as when they are turned on (b) but in this case, the supply of power to the main heater 2 is controlled by the high temperature thermostat 27 as a result of the low temperature thermostat 28 being shortcircuited. |
