Numerical simulation with ANSYS Fluent, Code Saturne and OpenFOAM is compared in terms of the problem of natural convection in enclosed volume of air in the presence of a heating element. A comparative analysis of software on the basis of three turbulence models (k-e, SST and WALE) is conducted. The results adequacy is assessed. Experimental data on the temperature profile in the central section are used as a benchmark criteria. Assumptions about the destructive factors reducing the accuracy of the solution are partly supported by the results of comparative analysis of the intensity of convective up-draught. A combined turbulence model k-ω SST is used to determine the effectiveness of the implementation of the wall function in Code Saturne and OpenFOAM for mesh with variable dimensionless distance in the range of 1 < y+ < 5 and 10 < y+ < 50.