| 摘要 |
PURPOSE:To prevent the temperature of service hot water from varying sharply due to a capacity switching operation by a method wherein a flow rate switching means adjustable in at least two switching stages is incorporated in a flow rate control device and is linked to a heating capacity swithing device. CONSTITUTION:A heat exchanger 1 for heating water is provided with a pair of burners 5 and 6 of different capacities and the heating capacity of the heat exchanger 1 is switched by the capacity switching device 4. The capacity switching device 4 is formed such that the heating capacity of the heat exchanger is switched by controlling three electromagnetic valves V1-V3. Further, a water supply pipe 2 is provided with the flow rate control device 15 incorporating therein the flow rate switching means 16 capable of adjusting the flow rate of water determined at each of the operating positions of a hot water temperature adjusting knob (not shown). The flow rate control device 15 is formed of a motor operated valve 17 and a control circuit 19 for a drive motor 18 driving the valve 17 and the flow rate switching means 16 is formed of a bridge circuit 22 connected with resistors 24 and 25 through switching elements 26 and 27 in parallel relationship with a volume 20 of the bridge circuit 22. |
