Heat exchanger

A heat exchanger comprising:

• (a) an outer chamber having an inlet and an outlet for passing a flow of air through the outer chamber,
• (b) an inner chamber disposed within said outer chamber having a second inlet and second outlet for passing a flow of gas through said inner chamber,
• (c) heat exchange tubes being arranged in said inner chamber whereby said flow of gas contacts the outer surface of said tubes, and wherein said heat exchange tubes include a first plurality of tubes disposed in a first section of said inner chamber closest to said second inlet, and a second plurality of tubes disposed in a second section of said inner chamber above said first section so that air passes through the heat exchange tubes in the first and second sections for higher heat exchange;
• (d) baffle means disposed between said inner and outer chambers for directing said flow of air from said inlet through said heat exchange tubes wherein said baffle means includes a horizontal plate joined between the inner and outer chambers at the juncture of the first and second sections and extending partially around the inner chamber to form an L-shaped opening whereby the flow of air enters the first plurality of tubes, then into said outer chamber and back into said heat exchange tubes whereby heat is exchanged between the air and gas flows.