In the present study, a heated vertical tube with a taper and circular inlet conditions is experimentally investigated. The relationship between the Nu and Ra numbers is determined. The Rayleigh number is stated using the uniform heat flux and mean wall temperature and calculated for each inlet condition. Corresponding Nusselt numbers are then obtained and compared across the different configurations. These profiles are also compared to assess the influence of inlet geometry on natural convection flow patterns. The simulation results are validated against experimental data, where air is used as the convective fluid. The Nusselt number was found to increase proportionally with the Rayleigh number, indicating improved convective heat transfer with increasing buoyancy effects. We find that uniform taper inlet conditions have a higher heat transfer rate as compared with simple inlet conditions.