Patent ID: 7823578

Claim:
A biomass stove comprising: a firebox having a ceiling portion opposite a bottom, a rear side opposite a front, and first and second opposing lateral sides which extend vertically between the bottom and the ceiling portion and from the front to the rear side; a firepot disposed within the firebox between the first and second lateral sides on the rear side between the bottom and the ceiling portion; a first plenum formed between the ceiling portion and a top side of a housing enclosing the firebox; an air intake assembly coupled along the bottom of the firebox; and at least one duct comprising a first plurality and a second plurality of tubes disposed within the firebox and extending vertically between the air intake assembly along the bottom of the firebox and the first plenum, the first plurality of tubes being spaced apart from one another and disposed along, but spaced from, the first lateral side between the front and rear side and positioned between the firepot and the first lateral side so as not to come between the firepot and the front of the firebox, and the second plurality of tubes being spaced apart from one another and disposed along, but spaced from, the second lateral side between the front and rear side and positioned between the firepot and the second lateral side so as not to come between the firepot and the front of the firebox; wherein the first plurality and second plurality of tubes provide a heat exchanging flow path for ambient air entering the at least one duct from an exterior environment via the air intake assembly and exiting through the first plenum to the exterior environment, wherein the ambient air is heated by heated gas produced by the firepot within the firebox as the ambient air passes through the first plurality and second plurality of tubes; a first vertical baffle disposed between the first plurality of tubes and the firepot and forming a first heat exchange duct with the first lateral side and a second vertical baffle disposed between the second plurality of tubes and the firepot and forming a second heat exchange duct with the second lateral side, the first and second vertical baffles having upper edges spaced from the ceiling portion so as to form corresponding cross-flow openings between the ceiling portion the upper edges of the first and second vertical baffles; a horizontal baffle extending between lower edges of the first and second vertical baffles so as to form an exhaust chamber between the horizontal baffle and the bottom of the firebox and a combustion chamber between the horizontal baffle and ceiling portion in which the firepot is positioned; and an exhaust configured to draw heated gas from the combustion chamber through the first and second heat exchange ducts via the corresponding cross-flow openings and into the exhaust chamber where the heated gas is vented from the biomass stove, wherein the heated gas heats the ambient air in the first and second pluralities of tubes as the heated gas flows through the first and second heat exchange ducts.