A pellet stove having a combustion assembly housing. Located within the housing in a vertical array are a primary combustion chamber, a secondary combustion chamber located below the primary combustion chamber, and an ash receptacle located below the secondary combustion chamber. The primary combustion chamber communicates with the secondary combustion chamber, and the secondary combustion chamber communicates with the ash receptacle. A pellet feed housing is located above the primary combustion chamber and has a feed plate configured to feed pellets directly into the primary combustion chamber along an inclined path. Air intake ducts communicate ambient air with the interior of the housing. The primary combustion chamber communicates with a combustion gas conduit that conducts combustion gases along an upwardly extending tortuous path to an exhaust stack to provide heating. A pivotal, latchable door is attached to the front of the combustion assembly housing.

A heating device, preferably for the combustion of biomass, in particular of pellets of biomass, in one aspect, includes a burner part and a heating part. The burner part includes a combustion chamber; a double-walled, internally hollow combustion-chamber wall, which has an upper opening leading above the combustion zone into the combustion chamber; a flue-gas duct which leads the flue gas downwards along the combustion chamber, wherein the flue-gas duct is followed by a heat-exchanger area including initially, a flat-tube flue-gas heat exchanger, then, a tertiary-air heat exchanger; a flue-gas ventilation stack, a radiant-heat exchanger located above the combustion chamber, a flue-gas flap at the upper end of the flue-gas duct, which, when open, connects the flue-gas duct to the stack. A flat-tube flue-gas heat exchanger of the heating part forms a heat-exchanger circuit with an exhaust-air heat exchanger with the same heat-transfer medium as the flat-tube flue-gas heat exchanger.