| 摘要 |
PURPOSE:To secure combustion in an amount unaffected by switching of a solenoid valve in a gas-fueled heat exchanger-based fluid-heating apparatus by providing the control means with a means capable of heating the fluid to a set temperature after as well as before the switching of the solenoid valve. CONSTITUTION:On the basis of a set temperature in a means for setting the temperature 35 and the temperature of the fluid detected by a means for detecting the temperature 31a the amount of the combustion is decided and, when a solenoid valve 22 is open, a proportional feed valve 25 is placed under a first control and, when the solenoid valve 22 is closed, the proportional feed valve 25 is under a second control. When the amount of combustion decided under the first control decreases to a first amount of combustion, the solenoid valve 22 is closed and the proportional feed valve 25 is placed under the second control simultaneously with increase of the electric current by a set value. Thus even when the solenoid valve 22 is closed and the fuel gas feed to the burner is routed by a by-pass 23 restrictively, the proportional feed valve 25 secures the fuel feed in the same amount as when the solenoid valve 22 is open. When the amount of combustion increases under the second control, the solenoid valve 22 is opened and the proportional feed valve 25 is switched to the first control. |
