The process of burning goes through two stages, gasification and combustion of wood gas. That is why BIOTEC burners have primary and secondary air supply. Through the secondary air supply nozzle more oxygen can be added in to the wood gas burning above the burner pot, which gives better combustion efficiency because the combustion of flow gases is complete. This also gives cleaner flow gases.
Pellets (A) are forwarded to the fire(B). All material is burned completely before it leaves the burner pot (C). In burners with horizontal forwarding or when the pellets are falling down in to the burning pot, the ash can be stopped from leaving the burner natural way. Too much ash in the burner pot can cause combustion problems. Usually this type of burner needs more maintenance and cleaning, at least once a week. Also bashing of fuel can vary very much.