In a number of combustion chambers, differentiation between radiation and convective heat transfer on the surface is a problem of substantial interest. The hemispherical radiation heat Aux meter proposed by Afgan and Leontiev [1] and patented by Afgan, Carvalho, Martins and Leontiev [2] has potential to be used as an instrument with sufficient accuracy to measure the difference between hemispherical radiation heat flux and convective heat flux in the respective environments. The hemispherical radiation flux meter is numerically analyzed with the aim of defining the optimal design parameters to be used for experimental verification. With a proper selection of the design parameters corresponding to the conditions encountered in the boiler furnace, it will be possible to measure with the same instrument the radiation heat flux and convective heat flux. Particular attention was focused on the discussion of the respective parameters of the Aux meter in order to meet corresponding requirements in different environments. Attention was focused on the effects of differences in main mass flow rate and blow-off gas mass Row rate, heat conductivity of the holder and porous filament and the difference in temperature between solid structure and fluid flow in the filament. For the selected parameters of the main flow and radiation heat flux range, the radiation heat flux meter was designed.