In this paper numerical simulation of combustion over a sample of a prevalent gas-burner, and effects of parameters such as environment geometry, main parameters of chimney, effect of free and forced convection on the environment, in radiation modelling situation and without radiation has been studied. Since offering proposals to improve the efficiency of a system is required for completing identification of the system, gas-burner is set in different cases in the environment to have better recognition of the manner of gas-burner heat transfer to the environment. For study of radiation effects, a geometric model considering radiative heat transfer and without radiation is simulated and the results compared together. Furthermore, the distribution of environmental temperature in normal conditions, and advert to mass fraction of combustion products are the other cases which have been studie