The pellet or chip burner is simply integrated into the customer’s existing infrastructure. No major modification of the heating equipment or the hot water/steam production network is required. The solution is based on a vertical semi-gasification process, which reduces the size of the burner and thus facilitates its retrofit into boilers, even in tight spaces. The ashes resulting from biomass combustion are largely recovered in the burner itself, upstream of the boiler. This significantly reduces particulate emissions in the exhaust gases.