Abstract: A fuel burning heater has a lower combustion chamber with a door at the front thereof and an upper heating chamber with a discharge port for products of combustion at the rear thereof. A common wall between the heating chamber and a portion of the combustion chamber defines a bottom for the heating chamber and at least a portion of a top for the combustion chamber. A discharge passageway through the common wall conveys products of combustion into the heating chamber with means directing at least a portion of the products of combustion toward the front of the heating chamber. Draft regulators in the lower portion of the door introduce controlled amounts of combustion air for fast burning and other draft regulators in the upper portion of the door introduce controlled amounts of combustion air for slow burning.