| 摘要 |
PURPOSE:To enable a combustion control circuit to be applied to a gas combustion unit having a different kind of gas and a different capability by a method wherein an adjusting circuit is provided for adjusting an electric current of a coil of an solenoid proportional valve in response to the type of gas and an upper limit current value of the coil can be changed in a plurality of high and low stages within a range less than an electric current supplying a maximum rated combustion amount for a burner. CONSTITUTION:An adjusting circuit 19 is operated such that each of resistors 20, 21 and 22 is applied for each of city gas, natural gas and propane gas, and a potential at a voltage dividing point C becomes a value corresponding to the type of gas by changing over a changing-over switch 23. A capability changing-over circuit 13 is operated such that if both switches 17 and 18 are opened, the resistors 14 and 15 are short circuited, the potential at the voltage dividing point C can be lowered most. If only the switch 17 is opened, the resistor 14 is short circuited and the potential at the voltage dividing point C can be higher than that of opened switches 17 and 15. If both switches 17 and 15 are opened, the potential at the voltage dividing point C can be the highest value. At last. an upper limit current value of a coil 2a of an solenoid proportional valve 2 can be changed over in three high and low stages within a range less than an electric current supplying the maximum rated combustion amount QM of the burner 1. |
