The paper concerns the analysis of the heat transfer process that occurred during solid fuel burning in fixed bed conditions. The subject of the analysis is a cylindrical combustion chamber with an output of 12 kW heating power equipped with a retort burner for hard coal and biomass combustion. During the research. a numerical and experimental study is performed. https://www.roneverhart.com/New-Balance-990v3-Red-Black-Grey-White-M990RW3/