Abstract: A device comprises a primary combustion space adjacent the fuel vaporizing portion of a porous body exposed thereto, and a secondary combustion space provided downstream from the primary combustion space. Of the primary air supply to the primary combustion space and the secondary air supply to the secondary combustion space, at least the flow of the primary air is regulated by an air regulator to steplessly vary the calorific value while maintaining satisfactory combustion.

Abstract: A device which includes a porous burner head capable of containing a liquid fuel in a liquid state and in which air is supplied to the surface of the burner head to vaporize and burn the fuel contained therein. The burner head is made of a heat-resistant porous material having extending therethrough minute channels which are predominantly up to 100 .mu.m in diameter and give the burner head a porosity of at least 25%. The burner head is capable of raising the liquid fuel at a rate of at least 0.001 g/cm.sup.2.min to a height of up to 70 mm. The use of the burner head assures clean combustion and high combustion efficiency.