Nowadays, thermal energy storage systems (TESS) are essential to rationalize the energy management and the use of environmental energy potential. Concepts including phase change material (PCM) are technically mature for building applications and innovations. Among the existing concepts of TESS, PCM to air heat exchanger can directly be integrated in building ventilation systems in order to store energy for heating peak loads shaving [1]. A similar system could also be used for cooling purposes, as presented in [2]. Here, during the off-peak period, the air is heated by a heat pump and passes through the heat exchanger to store energy. This energy is released during the peak period to heat the building and reduce the required heating load. The objective is to stop the heat pump without affecting the thermal indoor comfort. Quantitatively, the heat exchanger is designed so it can replace about a 1 kW heating system during 2 hours. The second issue of this work is to provide detailed results suitable with the validation of numerical models. On this subject, data from several experiments are collected and presented in [3] and the authors are underlining the lack of data. For this reason, the geometry of the exchanger will be detailed here and the uncertainty associated with the heating power measurement will be given. In this paper, the design and the instrumentation of the heat exchanger is first presented. Next, the tests simulating a ventilation system, and realized in our laboratory setup, are presented and discussed. In the conclusions, design guidelines are given in order to meet the storage unit specification requirements.