Nowadays all engineering technologies are based on the automation, but still there are some processes that are not easy to automate. One of them is the heating process using solid fuel boilers. The paper deals with automated double-link air flow control of the combustion process. The research target was to find more effective solutions of furnace air flow regulation to improve the combustion process efficiency. The research object was a 56 kW wood briquettes water heating boiler. The results of the experiment research show a higher efficiency of the combustion process with double-link air flow PI control using motor valves.

Future perspective of the research is the production of fuel pellets from energy plant (Phalaris arundinacea L., Festuca arundinacea, etc.) biomass, because it can be better burnt in granule burners and is more environmentally friendly, if compared to the fossil mineral resources (coal, oil, gas), moreover it has low moisture content (70 – 90 g kgE-1) and correspondingly it produces higher combustion energy. The research covered preparation of various content tablets from reed canary grass (Phalaris arundinacea L.) variety ’Marathon’ (N fertilizer rate on the N-90 kg haE-1), energy wood - osier (Salix viminalis L) and poplar (Populus tremula L.) with N fertilizer norms N-0 and N-120 kg haE-1, and afterwards research of the combustion ability of and ash content in these tablets. Combustion ability of reed canary grass (Phalaris arundinacea L.) variety ‘Marathon’ reached 17.48 MJ kgE-1. The highest average combustion ability with different pellet content was found for the fast-growing poplar both with doses of N fertilizer - 18.55 MJ kgE-1 and without N fertilizer - 18.49 MJ kgE-1. Optimum content of various component pellets for biomass was a mixture of components 1/3 (reed canary grass/osier or poplar). The lowest indicators in respect to the ash content were observed for osier (Salix viminalis L.) - 27.9 g kgE-1. The best ash content indicators for a mixture of granular composition was in a mixture of components one-fourth of the reed canary grass with three parts of osier - 34.3 g kgE-1 or with poplar - 41.8 g kgE-1.

Wood construction elements are widely used in buildings and they can be used in construction elements such as roofs, floorings, windows and doors. As wood is combustible material, there are lot of fire regulations that should be fulfilled at the design stage of any building project. In Latvia, as in some other countries usage of wood in building constructions is limited. Wood materials are an ecologically friendly material and a renewable resource, and its usage should be promoted. The paper presents an overview of heat distribution in wood floorings exposed to standard heat fluxes which is different compared to wood members exposed to high heat radiation. Fire spread and self-ignition investigation on wood floorings is carried out in this research. The results show different kinds of the temperature distribution in the cross section of the wood member cross section depending on heat radiation and location of the temperature measurement point. Temperature distributions in wood during fire can be completely different in dependence on heat radiation and cross section of the wood member. The wood materials in floorings do not reach the self-ignition temperature during standard heat radiation.