| 摘要 |
PURPOSE:To make it possible for a user to change the capacity only by operating a switch, by adding a switch for changing over the capacity of a water heater to a pressure control circuit, and making it possible to change over the output from a proportional valve control circuit. CONSTITUTION:When a switch 39 for changing over the capacity of a water heater is open, voltage at point E is equal to that at point A, while voltage at point D being the potential value by resistance 33, 34 for voltage at point F and a variable resistance 37; voltage at point E being the potential value by resistance 35, 36 for voltage at point B and a variable resistance 38; voltage at point C being the potential value by voltage at point E and resistance 31, 32 for voltage at point D. Accordingly, min. burning rate is determined by the voltage at point E. When the voltage at point E has been settled, max. burning rate will be determined only by the voltage at point D. When the switch 39 is closed, voltage at point F is the potential by resistance 40, 41 for voltage at point A, whereby min. burning rate does not change, while only max. burning rate becomes such value that corresponds to the ratio between resistance 40 and 41, which corresponds to the change of capacity of the water heater. Therefore, by providing a changeover switch 39, it is possible to change over the capacity without adjustment by means of a variable resistance. |
