The world's energy consumption has huge environmental and socioeconomic impacts. Heat storage allows the use of renewable energy in buildings to be increased and enhances their energy storage performance. Ettringite material has the advantage of high energy storage density at low temperature (60 degrees C) compared to existing adsorbent materials such as zeolites (around 200 degrees C). The objective of this study was to build and improve an experimental prototype of a thermochemical reactor to serve as a proof of concept. A previously modelled cylindrical thermochemical reactor with an axial metal tube was built in the laboratory. It was the first prototype, with a heat storage yield of 44% or storage capacity of 61 kWh/m(3). To improve the heat storage performance of the thermochemical reactor, a second prototype without the metal tube was also developed in the laboratory. The storage tests with this second prototype showed a heat storage yield increase from 44% to 71%, with a storage density of 117 kWh/m(3).