Abstract: In abstract a preferred embodiment of this invention is an improved fireplace heat exchanger in the form of an integral heat exchange system, fireplace closure, air tight glass doors and an outside air introduction system. The unit is built as a single unit and is installed as such either in new construction or preexisting fireplaces. The invention also includes a unique door locking system to assure air tight integrity between the interior of the house and the fire in the fireplace.