Gas furnace

The invention relates to the technical field of combustors, in particular to a gas furnace, an outer pipe is inserted into the side wall of a furnace body, an inner pipe is arranged in the outer pipe, an impeller mechanism is rotatably mounted in the inner pipe, a plug is located on the side, facing the furnace body, of the impeller mechanism and slidably connected with the impeller mechanism, and a flow channel is formed in the impeller mechanism. The blocking piece is adjacent to the impeller mechanism and forms a barrier on the flow channel, the blocking piece and the outer pipe are connected through the reset spring, the elastic piece is connected with the blocking piece and the inner pipe, the outer pipe is provided with a combustion cavity adjacent to the furnace body, the scraping strip is attached to the inner wall of the combustion cavity, and a transmission mechanism is connected between the scraping strip and the blocking piece. And when the blocking piece moves towards the impeller mechanism, the