This book examines key issues in improving the efficiency of small and medium power boiler units by adding control systems for the fuel combustion process. The original models, algorithms, software and hardware of the system developed for controlling the fuel combustion process are presented. In turn, the book presents a methodology for assessing the influence of climatic factors on the combustion process, and proposes new methods for measuring the thermophysical characteristics, which require taking into account the concentration of oxygen in the air. The system developed here was implemented on a boiler of the NIISTU-5 type, which is widely used for heat power engineering in Ukraine and other Eastern European countries. Given its scope, the book offers a valuable asset for researchers and engineers, as well as lecturers and graduate students at higher education institutions dealing with heat engineering equipment.