The textbook contains a classification of boiler units and heat generators. The normative methodology of thermal calculation of the boiler unit is presented, the methods of calculation of principal thermal schemes of heat generating plants, harmful emissions from boiler houses and the minimum required height of the chimney and aerodynamic calculation of the gas-air path of the boiler unit are described. For the convenience of work, the manual provides the necessary explanations of formulas, tables, nomograms, figures and a large amount of regulatory data.