Wood burning stove

A stove or furnace unit for use with solid hydrocarbon fuels, said unit including a metal shell and a junction dividing said shell into upper and lower chambers and having a central, substantially horizontal port effecting communication between said chambers, said junction including upper and lower portions defining the proximate ends of the upper and lower chambers, respectively, at least the lower portion of said junction metal and connected to said shell a substantial distance from the outer edge of the upper portion, said upper chamber having a flue outlet, said lower chamber shaped and dimensioned to establish a primary combustion chamber to accommodate and support a charge of fuel of predetermined maximum dimensions and volume and having a normally closed opening for use in the introduction of the fuel, said lower chamber also having air inlet means so dimensioned and disposed that the natural draft attending the burning of the charge induces an inflow volume of air adequate to support the complete combustion of the charge including pyrolytic products with at least a substantial portion of the induced air entering the combustion zone laterally of the fuel charge in a manner such that combustion of the fuel is attended by a multitude of upwardly flowing streams of different types, one type containing unburned volatile hydrocarbons and oxygen poor air and another consisting of oxygen rich air, the vertical distance between the base of the supported fuel charge and the port so approximately 0.25 to 1.5 times the maximum lateral dimension of said lower chamber in the zone of said fuel charge so that during the normal operation of the unit, said port is in the flame front, a substantial portion of the oxygen rich air stream remain independent of the other streams but is heated and carried upwardly thereby, said port of an area approximately 0.05 to 0.35 times the cross sectional area of the lower chamber in the zone of said fuel charge so that the rising streams are suddenly contracted as they approach and enter the port and are suddenly expanded as they exit therefrom and during such contraction and expansion said streams become turbulently and intimately mixed but with a substantial volume of heated oxygen rich air entering the upper chamber with combustion of the volatile hydrocarbons occurring in a secondary combustion zone including the upper portion of the lower chamber and the lower portion of the upper chamber, said junction constituting a barrier against heat loss through the metal shell that would interfere with the combustion of volatile hydrocarbons in the lower portion of the upper chamber, said upper chamber of a cross sectional area and height such that combustion is complete therein without any substantial impingement of flame on wall metal structure of said secondary combustion zone at least in the lower portion of said upper chamber and the upper portion of the upper chamber constituting a heat exchanging zone.