The object of the study is a new micromodule gas burner for small hot water boilers, in which, to stabilize combustion, the phenomena of flow disruption due to sudden expansion at the outlet of the burner are used. Today, there is an urgent task related to the development of new technical solutions for the most efficient and environmentally pure combustion of fuel in power plants, particularly, it is necessary to pay special attention to the stabilization of the flare. The combustion characteristics in this burner have been studied experimentally and theoretically, calculations are given for modeling a micromodule gas burner with a sudden expansion at the outlet, in particular, the model of a burner device for burning natural gas (propane) was modeled in the Ansys Fluent 2021 R1 software package. As a result of the experiment, the length of the torch was reduced, as well as the concentrations of harmful NOx emissions were reduced with improved indicators of combustion completeness and temperature uniformity of the field. The results of experiments with different nozzles are presented, namely nozzles with slots at the outlet d1 – 0.12 m and d2 – 0.15 m. The number of modes in each experiment is 5. Mathematical modeling of this burner with the possibility of evaluating the effectiveness of these measures will allow us to develop optimal operating modes of power plants and develop new technical solutions to reduce the emission of pollutants. Based on the experimental data obtained, graphs were constructed (completeness of combustion, temperature unevenness, concentration of substances), and the results were summarized. In general, these characteristics will increase the efficiency of using this burner in hot water boilers