Combution air is drawn directly from outdoors through an internal air inlet tube (A) to the air distribution collar (B). The door (C) prevents air from being drawn from the room. The door is insulated to prevent heat loss and includes an air-cooled heat shield to prevent hot surfaces near the user. Combustion air from the collar flows through an upper and lower nozzles (D) into the combustion chamber (E). Remaining free air is mixed with hot gases before entering the ceramic secondary combustion chamber (F). Within the ceramic chamber, smoke, creosote and particulates are burned at temperatures near and above 2000 ºF. The hot gases release their heat as they move through a 5 pass tubular heat exchanger (G) submerged within a large volume of water. The cooled gases are then pulled into the Draft Inducer housing (H) and pushed out of the exhaust pipe (I).