PURPOSE: To enable a burner to always perform combustion under a normal state even when a voltage is decreased or the property of fuel is changed, by a method wherein an amount of the air for combustion set to a value suitable for a fuel amount is made controllable by proportionally varying the combustion air amount through the manipulation of a control knob.

CONSTITUTION: A light lamp 5 is provided for lighting in a proper fuel amount position of an amount of fuel fed to the interior of a burner 1 through control of a test operation switch 4, and an airflow regulating knob 6 is provided for regulating an amount of the air for combustion, fed by a blower 3, so that a combustion airflow is regulated to a value suitable to a fuel amount prevailing during each lighting of the lamp 5. Through the control by the knob 6, a combustion airflow is set to a value suitable to a fuel amount during each lighting of the lamp 5. The set combustion airflow is stored in a control device 7, and a combustion airflow ranging throughout the whole area of a combustion amount burnt in the burner 1 by means of the stored combustion airflow during each lighting is stored in the control device 7. A combustion airflow amount ranging throughout the whole area of a fuel amount set and stored in the device 7 is proportionally varied and controlled through the manipulation of the control knob 8.