Abstract The conventional models used to predict the heat transfer in the Trombe wall are based on the assumption of a uniform temperature distribution from bottom to top of the Trombe wall and on a one-dimensional model in the case of convection heat transfer. Experimental investigations indicate that these assumptions are not suitable for precise analysis. This paper describes an extended two-dimensional model used to compute the heat transfer and the experimental verification. The investigations revealed that convection heat transfer in the Trombe channel depends upon the distance from the bottom vents in a similar way as convention heat transfer in the entrance region in air ducts, instead of on relations derived from free convection heat transfer research along vertical heated plates.