PURPOSE: To retrieve waste heat by a method wherein the inner tube of an exhaust double tube is utilized as the path of exhaust gas and air is supplied by a fan into a path between the inner and outer tubes to discharge it into a room.

CONSTITUTION: The exhaust gas of a kerosene stove 17 passes through an exhaust tube 15, an exhaust gas path at the inside of air supplying and discharging double tube 13, 12, 11, the exhaust tube 3 of main body and a heat radiating tube 4 and is released to the outside of the room. On the other hand, fresh air of the outside of the room is sucked from an air supplying port 8 simultaneously with the releasing of exhaust gas by the fan 2 and is sent into the air supplying path at the outside of the air supplying and exhausting double tubes 11, 12, 13, thereafter, is released into the room through the supplying air discharging port 14.