PURPOSE: To eliminate the defects such as the occurrence of poor combustion, the increase of burner size and the like and at the same time facilitate the cleaning of a trivet support by a method wherein the areas of a secondary air flow passage and of the flow passage of a secondary air port in the combustion part of a stove are controlled so as to control the secondary air flow rates supplied to said passages in order to increase the flow rate of the secondary air supplied through the secondary air port.

CONSTITUTION: Secondary air necessary for combustion is supplied through a gap 6, a secondary air supplying port 24 and a trivet 7 part due to draft power. At this time, the flow rate of the secondary air supplied from a secondary air flow passage 8 to a burner 1 is decreased, because a trivet support 28 is provided in the secondary air flow passage 8 so as to increase the resistance of the secondary air flow passage 8 by a vena contracta part 33, at which the secondary air flow passage is locally throttled in order to reduce the draft power applied to the secondary air flow passage 8. On the contrary, the resistance of a secondary air port 4 becomes smaller as compared with that of the secondary air flow passage provided with the vena contracta part 33, resulting in increasing the flow rate of secondary air supplied to the secondary air port 4.