PURPOSE: To ensure that a briquette can be easily ignited by a single igniting operation owing to a flame spreading effect of a flame stabilizing baffle, by a method wherein a flame stablizing baffle provided with flame holding holes is placed in a combustion cylinder at such a height as to leave a predetermined spacing from the upper surface of each briquette.

CONSTITUTION: In a burner unitIadapted to hold a plurality of briquettes in parallel in a casing main body 1, the combustion cylinder 21 is provided in the casing main body 1 at a position directly above the burner unitIso that the cylinder 21 is located at an upper part of the burner unitI. The flame stabilizing baffle 23 provided with the flame holding holes 22b is placed in the combustion cylinder 21 at the height such as to leave a predetermined spacing from the upper surface of each of the briquettes. Accordingly, air in the combustion chamber and air in an oven chamber 7 in which a heat exchanger 25 is located are heat-exchanged and blown off from a hot air blow-off port 2 by a hot air blower 5.