The stages of fuel combustion require taking several precautions to reduce incomplete combustion, which decrease the boiler’s efficiency. First step is the fuel input into the combustion chamber. Generally, the more fuel is introduced in a single moment, the more heat is needed to evaporate the moisture contained in the fuel. Good approach in this case is more continuous fuel feeding, i.e. smaller amount of the fuel for a longer period of feeding. This is in contradiction with real behavior of the controllers that usually only allow timed feeding of a fuel batch. The most important point regarding combustion efficiency is the volatile matter release and burning. The rapid release of volatiles means that there is necessity of quite large amount of air to be mixed with the released gas within the hot zone