Replacing fossil fuel by solar energy as a promising sustainable energy source, is of high interest, for both electricity and heat generation. However, to reach high thermal solar fractions and to overcome the mismatch between supply and demand of solar heat, long term heat storage is necessary. A promising method for long term heat storage is to use thermochemical materials, TCMs. The reversible adsorption-desorption reactions, which are exothermic in the hydration direction and endothermic in the reverse dehydration direction, can be used to store heat. A 250L setup based on a gas-solid reaction between water-zeolite 13X is designed and tested. Humid air is introduced to a packed bed reactor filled with dehydrated material and by the resulting adsorption of water vapour on TCM, heat is released. The reactor consists of four segments of 62.5L each, which can be operated in different modes. The temperature is measured at several locations to gain insight into the effect of segmentation. Experiments are performed for hydration-dehydration cycles in different modes. Using the temperatures measured at different locations in the system, a complete thermal picture of the system is calculated, including thermal powers of the segments. A maximum power of around 4kW is obtained by running the segments in parallel mode. Compactness and robustness are two important factors for the successful introduction of heat storage systems in the built environment, and both can be met by reactor segmentation. With the segmented reactor concept, a high flexibility can be achieved in the performance of a heat storage system, while still being compact.