A biomass pellet combustion system includes a primary burn chamber, a coal burn chamber, and a gas burn chamber. The primary burn chamber is configured to receive pellets from a drop tube of the biomass pellet combustion system. The coal burn chamber is configured to receive coals from the primary burn chamber. The gas burn chamber is configured to receive combustible gases from both the primary burn chamber and the coal burn chamber, wherein a secondary combustion process converts secondary combustion air and the combustible gases into exhaust gases in the gas burn chamber.