| 摘要 |
PROBLEM TO BE SOLVED: To effectively suppress occurrence of hunting which tends to occur due to a difference of combustion capacity during flame holding control in a combustion apparatus in which the combustion capacity of an entire burner unit is switched by changing a combination of burners to which combustion gas is supplied.SOLUTION: A combustion apparatus includes: a burner unit 2; a combustion fan 4; a proportional valve 7 arranged in a gas supply passage 5; and capacity change-over valves 8- 8for switching combustion capacity of the entire burner unit. When a required combustion amount exceeds an upper limit of combustion amount obtained by current combustion capacity or falls below a lower limit, capacity increase control or capacity decrease control is performed. Until predetermined time passes after the capacity increase control has been executed, flame holding control is performed to make the rotational frequency of the combustion fan lower than a value corresponding to the required combustion amount while a proportional valve current is maintained at a value corresponding to the required combustion amount. During the flame holding control, a lower limit value of the proportional valve current is made lower than that when the flame holding control is not being executed.SELECTED DRAWING: Figure 1 |
