| 摘要 |
PURPOSE:To enable to obtain a water temperature stabilized as early as possible after the start-up of water supply, by arranging such that an original flow rate of gas at the time of shift after the termination of slowed ignition into a PID control may be switched depending on the flow rate of water. CONSTITUTION:When the flow rate of water is increased by adjusting a flow switch and a valve 12 is turned by a water flow in the directions of reed switches 16a, 16b, the reed switch 16a having no magnetic body 18 is first actuated, whereas the reed switch 16b will not be actuated because magnetic forces from a magnet 14 are attenuated by the magnetic body 18. With the further increase of flow rate, the valve 12 shifts closer to reed switches 16a and 16b and consequently the switch 16b is actuated under ample magnetic forces from the magnet 14. As a result, a water flow switch 3a can detect two flow rates - larger and smaller ones. The adjustment of operating flow rate can be made by varying the size and position of magnetic body 18. Signals from a temperature sensor 2 and a valve controlling section 21 are also inputted to a PID controlling section 20, and the PID control is interrupted unless a small flow rate signal a is outputted from the reed switch 16a. |
