Lennox Industries Inc.

Mark R Rakowski

John W Whitesitt

John H Wiker

Rodney S Roan

Myron C Oglesby, Jr

A furnace is adapted for operation in downflow, left horizontal flow and right horizontal flow positions. The furnace includes plural burners, a two-stage heat exchanger, a header box at the heat exchanger outlet for collecting products of combustion from the heat exchanger, and an inducer for inducing a flow of products of combustion through the heat exchanger. A condensate drain and trap are also provided for draining condensation from the header box and from an exhaust vent through which products of combustion are exhausted from the furnace. In accordance with one feature of the invention, a manifold is located inside the header box to divide the header box into first and second chambers. A pressure sensor senses differential fluid pressure between the first and second chambers for detecting a blocked condensate drain condition. In accordance with another feature of the invention, an intake air manifold located between a combustion air intake duct and an enclosure housing the burners includes opposed inlet openings and an outlet opening. A perforated baffle is positioned between the inlet openings for interrupting air flow between the inlet openings and cooperates with another perforated baffle in the burner enclosure to distribute combustion air to the burners. In accordance with still another feature of the invention, the furnace is provided with a condensate trap which is operable either in a vertical or a horizontal orientation, depending upon the position of the furnace. The trap is always installed in the same position relative to a furnace connector fitting, but is operable in either a vertical or horizontal orientation to accommodate both downflow and horizontal flow operation of the furnace.

Multi-position furnace with condensing heat exchanger

A device for inhibiting NOx production is disposed in a gas furnace combustion chamber. The device includes a baffle member for dividing the combustion chamber into first and second regions. A fuel-rich mixture of gas and primary combustion air is ignited by an inshot burner and the flame is drawn into the combustion chamber by an induced draft blower along with secondary combustion air. The combustion chamber is configured such that in the first region (i.e., upstream of the baffle member) turbulent mixing of the secondary combustion air with the flame is inhibited to maintain a relatively gas-rich flame. The baffle member channels the flame and secondary combustion air into a convergent flow path and the passage of the flame and secondary combustion air over the baffle member creates turbulence, which enhances mixing between the flame and secondary combustion air in the second region of the combustion chamber (i.e., downstream of the baffle member). The turbulent mixing effects substantially complete combustion of the gas/air mixture. Because the turbulent mixing occurs at a location farther along the flame path in the combustion chamber than in conventional gas furnaces, the flame temperature remains relatively low throughout the combustion chamber, thereby inhibiting NOx production.

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Frisco, TX, United States of America

Mark R Rakowski