Stack-type heat exchanger

An improved heat exchanger device disposed in a stack through which heated gases are vented from a heat generating source, the improvement comprising in combination

• a heat exchanger tube section for the heating and passage therethrough of clean input air,
• a motor driven fan unit disposed in a fan section connected to and communicating with said tube section, said fan unit drawing said clean input air from a location outside or inside of the building in which said heat generating source is located and forcing said air into and through said tube section,
• and coupling and transition members conjoining said tube section to and for communication with stack portions thereabove and therebelow,
• said tube section comprising a housing for and a plurality of spaced apart clean air conducting tubes disposed therein transversely of the flow direction of the vented stack gases,
• said housing defining a chamber therein for said stack gases to pass therethrough and over and about said tubes therein to heat said tubes and the clean air passing therethrough,
• said tubes communicating at their input ends with said fan section to receive said clean air therefrom and conducting said air through said tube section housing to the output ends of said tubes for discharge of heated clean air from said tube section,
• said tubes each having a damper plate attached thereto at its output end to modify and restrict the output orifice of said tube so as to generate a positive air pressure in each of said tubes at a valve above and in excess of the static pressure of said vented stack gases passing through said chamber,
• whereby to prevent said vented stack gases from entering said clean air conducting tubes.