Wood and coal burning heating unit

Claim 1

A wood or coal burning, heating unit comprising a firebox having a bottom, spaced upright side walls, a back wall interconnecting the side walls, a front wall interconnecting the side walls and having a door opening therethrough, and a sheet metal top interconnecting said side, back and front walls, said sheet metal top forming substantially the entire top of said firebox, whereby the interior of said firebox will serve as a combustion chamber; a back outer wall forming a back chamber with the back wall of the firebox; an air inlet duct connected into the back chamber; means for providing a flow of air through the air inlet duct and into the back chamber; an outer top wall spaced from said sheet metal top of said firebox, with said front wall and said spaced upright side walls extending upwardly beyond said firebox to interconnect with the front edge and side edges, respectively, of said outer top wall to form a top chamber positioned over and covering substantially the entire top of the firebox; means for connecting the upper end of said back chamber in flow communication with said top chamber so that air can flow from said back chamber to said top chamber; a substantially rectangular opening along the top of the front wall of said heating unit communicating directly with said top chamber, said opening facing from the front of the heating unit so that heated air flows from said top chamber outwardly from the rectangular opening in the top of the front wall of said heating unit; a plurality of spaced apart, elongate, upstanding metal fins welded to said sheet metal top of said firebox said fins being disposed upwardly from said sheet metal top into said top chamber to form flow channels in said top chamber between mutually adjacent fins so that the flow of air through said top chamber passes through said flow channels, whereby heat is conducted through said fins from said sheet metal top of said firebox and then transferred from the fins to the air flowing through said flow channels; and door means connected to the front wall of said firebox and adapted to close the door opening therein.