The results of an experimental study of a free convective boundary layer on a vertical heated surface are presented in this paper. Particular attention has been paid to investigation of the laminar-turbulent transition zone and determination of the zone boundaries. The main goal of the present work was to find the opportunity of the transition processes’ control by using various large-scale obstacles located in the region of the laminar section of the boundary layer. A vertical aluminum plate 90 cm wide and 4.95 m high served as a free-convection flow generator. Based on the obtained results, it is safe to state that there is a possibility of a significant reduction in the length of the transition zone through the use of large-scale obstacles. This way permits the beginning of the region with developed turbulent heat transfer to be moved nearer to the front edge of the surface. Thus, these obstacles can be considered as passive elements for controlling the heat transfer intensity.