the resistance of the side walls in this specification we would define the shape of the burnpot as a generally truncated inverted funnel shape with the understanding that this would encompass many geometries such as an inverted truncated cone or a truncated pyramid with a truncated top that is smaller than the operable bottom to be operable it is necessary for the clinker which in the case of a corn burning stove will frequently be one solid mass of byproducts of combustion to drop out of the bottom rather than sticking to the sides as would be the case generally with vertical walls or funnel shaped walls with a smaller bottom than top the combustible air system 48 in fig2 includes the exhaust blower 78 a heat exchanger system 38 and outlet pipes 88 to permit exhaust to flow out of a housing for the stove and inhabitants into the outside atmosphere the heat exchanger system 38 includes an upper heat exchanger 40 generally positioned horizontally and a back heat exchanger 44 generally positioned vertically with this arrangement the combustible air follows a flow path from the inlet 80 a in the direction of the arrows to 80 b downwardly to 80 c where it passes into the openable bottom 52 of the burnpot 26 and through the apertures 72 in the side wall portions of the burnpot 26 to support combustion therein and then upwardly as shown at 80 d around the heat.