In this paper, a method for calibrating a boiling-meter is carried out. It uses a combined experimental and numerical simulation approach to ensure consistency of results. For this, experiments were carried out in a boiling cell containing a Fluor inert (FC-72) liquid topped with a gas canopy. The liquid is heated using a heat source installed in a boiling cell, enabling heat transfer to be measured at the surface of the cell walls. Experiments were carried out under well-controlled operating conditions. The obtained experimental results were compared with literature correlations. Good agreement was observed under certain steady-state conditions, but often with limited precision. Numerical simulations of the experiment were carried out using Star CCM + software, taking into account convection flows in three-dimensional geometry. The results of the numerical and experimental simulations are in good agreement throughout the entire warm-up period until a steady state is reached. The robustness of these results led to an analysis of convection flows in the experimental cell. Preliminary results have revealed flow structures that explain the differences in heat transfer to the walls, depending on the orientation of the boiling-meter relative to gravity.