The invention relates to a combustion furnace for solid fuels, particularly a chimney stove, having a supply chamber for the fuel underneath the combustion chamber (1). The supply chamber is constructed as a shaft (4), in which the height of a grating (3), as a platform for the fuel supply, can be adjusted. To this end, a lifting mechanism is provided, which can be operated directly by means of one or more spindles or toothed racks and a crank (6) or indirectly by a motor. The lifting speed, i.e. the replenishment of fuel material, can be controlled on the basis of the temperature, a temperature sensor (12) for the exhaust gas temperature being provided next to the flue (2).