Heat transfer models in multiphase flow with wall boiling rely on closure relations for bubble departure and lift-off diameters. The approach proposed in this paper reassesses the physical representation of each term of the force balance model, eliminating inconsistent assumptions and redundant calibration, leading to a more general methodology to predict lift-off and departure diameters. The validation against available datasets shows improved applicability when compared to existing models. The mechanistic model proposed in this work is expected to be implemented in CFD codes, to improve predictive performance of heat partitioning models. (C) 2017 Elsevier Ltd. All rights reserved.