Industrial oven having air recirculating means for minimizing heat loss

In an industrial oven for heat treating a series of articles and comprising

• a tunnel enclosure having a tunnel space therein through which the articles to be heat treated may pass,
• said tunnel enclosure having sidewalls and upper and lower walls,
• said sidewalls including terminal walls having access openings through which the articles to be heat treated may pass into and out of said tunnel space,
• conveyor means for carrying the articles through said access openings and said tunnel space,
• heating means for supplying heat to said tunnel space to heat treat the articles,
• the improvement in that each of said terminal walls is provided with a nozzle disposed within the tunnel enclosure adjacent to the upper wall and said corresponding terminal wall and communicating with said tunnel space for directing a stream of hot air downwardly across the corresponding access opening in the corresponding terminal wall,
• said nozzle being angled downwardly into said tunnel space and away from the corresponding access opening to resist the escape of hot air from said tunnel space through such access opening,
• an exhaust structure having an exhaust opening disposed in the upper wall of said tunnel enclosure adjacent to and interior of said nozzle to provide for the lowering of the air pressure in said tunnel space near the upper portion of the corresponding access opening,
• and air handling means for withdrawing hot air from said tunnel space through said exhaust opening while blowing hot air into said tunnel space through said nozzle for minimizing the escape of hot air from said tunnel space through the corresponding access opening.