HOT AIR FURNACE

PROBLEM TO BE SOLVED: To prevent poisonous gas generated when fuel is ignited from being mixed with hot air for heating operation by a method wherein there is provided a structure in which a combustion chamber and a hot air chamber are separated and a plurality of panels through which combustion gas generated from the combustion chamber are passed in the hot air chamber. SOLUTION: Combustion gas is not leaked out except a combustion chamber 1 and a discharging chamber 3. In addition, a hot air passage 20 is placed to be adjacent to a combustion gas passage 19. A lower side of the hot air passage 20 is separated by a partition wall 5 from the combustion chamber 1 and its upper side is separated by a partition wall 12 from an air discharging chamber 3. However, one of the side portions is communicated with an air supplying port and the other of the side portions is communicated with a hot air blowing-out port. In addition, a panel 9 is of a thin-walled cylindrical structure in which two folded thermal radiation plates are faced to each other in a predetermined space, wherein the combustion chamber 1 and the air discharging chamber 3 are connected like a duct form to make either the combustion gas passage 19 or the hot air passage 20.