Abstract: A fireplace heating unit having a stainless steel firebox mounted within a double-walled housing, the firebox and housing being constructed and arranged to provide an inner air chamber communicating with outside air; and an outer air chamber communicating with the interior of the room being heated. The outside air is heated by the walls of the firebox and a portion of the heated air is directed into the firebox to be used as combustion air, and the remainder of the heated outside air is directed into the room to be heated. An insulated wall is provided between the inner and outer air chambers to maintain the air in the inner chamber at an extremely high temperature so that the combustion air ignites the exhaust gases in the fireplace thereby eliminating smoke from issuing through the stack.