The basic objective of this paper is the presentation of a numerical model for the mixing of an inclined submerged heated plane water jet in calm fluid, which has some improvements over similar models presented by various other investigators. The basic features of our model are: the conservation of heat flux instead of conservation of the buoyancy flux, the inclusion of the turbulent heat flux integrated across the jet, and the modification to include entrainment coefficient depending on the local Richardson number. This model predicts with reasonable accuracy experimental results regarding the axial dilution and the trajectory.