The basic principle of steam sterilization is based on high heat transfer rates from the steam to the medical device. In order to carry out this process as well as possible, the walls of the pressure chamber must be preheated. One way is to heat it with steam from the inside. To investigate this process, a three‐phase CFD model was developed, which can be used to determine the saturation temperature as a function of the partial pressure using a user‐defined function. For validation, the pressure, temperature (fluid and solid) and condensate content were measured. Results show that the model is excellently suited for predicting all relevant variables.