| 摘要 |
Improved Apparatus and Method for Water Heating Control A water heating system, including both a conventional water heater and an external heat source such as a heat pump, is controlled in accordance with the present invention. The water heater includes a water storage tank, an electrically resistive heating element located in the tank, and a tank-mounted thermostat which closes in response to a demand for water heating to allow electric current flow to the heating element and which opens when the demand for water heating has been satisfied, to interrupt the electric current flow to the heating element. The external heat pump includes a water pump for circulating the water between the storage tank and the heat pump, whereby water is heated by the heat pump and returned to the tank. A current sensor is provided for sensing the flow of electric current to the heating element and a temperature sensor is located external to the water storage tank for sensing the temperatureof the water entering the heat pump before the water is heated thereby. When the current sensor senses a flow of electric current to the heating element, thecurrent flow is interrupted so as to disable the heating element and the heat pump is enabled to provide the primary source of heating. The heat pump is operated until the temperature of the incoming water exceeds a predetermined set temperature. When this conditions occurs, the heat pump is deactivated and the heating element is enabled for a predetermined period to satisfy any additional water heating demand. The heating element is therefore used only to "boost" the water temperature to the desired temperature if the heat pump has not heated or is unable to heat the water to the required temperature. |
