Numerical and experimental results obtained for the steady-state flow in a thin vertical liquid layer heated locally from below are discussed. Based on these results, two laminar regimes at Rayleigh numbers from Ra = 10(2)-10(7) have been distinguished. The first regime is characterized by a symmetric two roll convective pattern. As soon as the Rayleigh number exceeds some critical value, the mirror symmetry is broken, and convective plumes tilt. A deflection of convective plumes from the vertical affects heat transfer conditions, and therefore this behaviour can be viewed as a second laminar regime. The location of the boundary between these two laminar regimes is considered in relation to the heat conduction at lateral boundaries, the aspect ratio of sides, the heater size, and the thickness of a working liquid layer. (C) 2017 Elsevier Ltd. All rights reserved.