Abstract: The assembly is adapted for installation as a free standing unit, a fireplace insert or a whole masonry fireplace. It comprises a primary combustion chamber, similar to a traditional fireplace, with the back wall of the primary combustion chamber being a common wall shared with a second combustion chamber. The secondary combustion chamber is vertical and discharges directly into the hood. The primary combustion chamber is vertical from the grates to the hood, where the flue gasses are forced to travel horizontally the depth of the grates and then enter the hood. The gasses from the primary chamber then mix with the heated gasses from the secondary chamber and reignite to initiate tertiary combustion. An angled grate is used and the grate is even with the intake of the secondary combustion chamber, which causes a horizontal draft to occur over the fire. An air duct, originating out of doors, is attached to the base of the assembly. The entire base of the fireplace is an outside air manifold.