US Patent 7823578 High efficiency biomass stove

A biomass stove includes a housing enclosing a firebox that defines a ceiling portion opposite a bottom, a firepot disposed within the firebox, an air intake assembly coupled to the firebox, and at least one duct disposed entirely inside the firebox and extending between the ceiling portion of the firebox and the air intake assembly. The duct(s) provide a heat exchanging flow path for ambient air entering the air intake assembly, where the ambient air is heated within the duct(s) prior to exiting through the ceiling portion of the biomass stove.