In this brief note, we have carried out an analysis of the temperature field inside a solar storage tank without any specific stratification device. The purpose of this study is to verify the ability of TRNSYS's Types 60 and 140 to reproduce the temperature field in the storage tank, so as to use one of these type in a large solar system, and to analyze fluid motion by means of CFD simulations. This part has highlighted the mixing in the top of the tank due to the inlet configuration, but also the limits of the stratified fluid models with the multinode approach used in TRNSYS. The validation of a global model for a large solar system using Type 140 will be done later. (c) 2004 Elsevier Ltd. All rights reserved.