The paper is devoted to description of evaporative convection in a long narrow horizontal channel filled by two binary mixtures contacting through the interface. The parameters of flow at weak evaporation of the lighter component of liquid from the lower layer to the upper gas layer are under study. For the calculation of velocities, temperatures, and concentrations changes in both layers the Navier-Stokes equations in the Oberbeck-Boussinesq approximation
supplied by heat and mass-transfer equations are used (the so-called two-sided model). Four modes of thermal load
distributed on the channel walls are considered (heating of both walls, only one wall or full thermoinsulation). The
comparison of influence of heating modes on the flow behavior is treated based on analysis of the exact solution of the boundary-value problems for the governing equations.