Heating system with exterior air inlet for combustion chamber

Claim 1

In combination with a building and a furnace for heating said building including a combustion chamber having an outlet and a flue connected to said outlet leading from said chamber to exteriorly of said building for escape of exhaust gases, first means leading from said combustion chamber to allow air to pass therethrough to said chamber, said furnace further includes a heating passage adjacent said combustion chamber, cold air ducts connected to said furnace which lead from interiorly in said building to said heating passage, and hot air ducts connected to said furnace which lead from said combustion chamber terminating within said building, means mounted in said passage operable to force air from said cold air ducts through said heating passage and out said hot air ducts, an air inlet duct connected to said furnace at said first means and extending exteriorly of said building allowing air outside said building to pass therethrough to said combustion chamber for combustion purposes, said air inlet duct and said first means and said combustion chamber being constructed to allow air flow into said chamber only through said air inlet duct; said furnace includes a first wall, a pair of said walls and a bottom wall connected together with said first means including a plurality of tubes mounted to said first wall and extending outwardly directly from said combustion chamber, wherein the improvement comprises: said furnace further including enclosure walls mounted to said side walls, said bottom wall and said first wall defining an enclosure into which said tubes open, said air inlet duct is connected to one of said enclosure walls allowing air from externally of said building to pass therethrough into said enclosure, said enclosure is sealed to allow air to enter said combustion chamber only from said air inlet duct; said air inlet duct is mounted at one end to one of said enclosure walls at an opposite end to an exterior side wAll of said building, said side wall of said building including a grate mounted to said opposite end of said air inlet duct; a filter mounted to said air inlet duct which filters incoming exterior air passing through said air inlet duct and wherein: said furnace is a forced air down draft furnace; first valve means mounted in said air inlet duct operable to control the amount of incoming exterior air passing into said combustion chamber.