In the heating central heat flow meters are installed in every circuit. Additional temperature sensors allow for measurement of flow and return temperatures to or from buffer store (B), heat pump (HP) and vessel (V), see Fig. 8. At the heat exchanger between the circuit of the store and the collector field anti-fouling units are installed. The effectiveness of the anti-fouling device is determined by monitoring the heat transfer coefficient (UA) of two identical heat exchangers, one with and one without the anti-fouling electrode. A meteorological station allows the monitoring of the ambient temperature, the irradiation, and wind velocity.

The store and the surrounding soil are equipped with several Pt100 temperature sensors, see Fig. 9. Additionally, heat flux sensors are placed at several locations in the envelope of the store in order to determine the local thermal losses. The hydraulic behaviour at charging and discharging via the two wells with regard to vertical and horizontal stratification will be one of several investigations. CFD simulations will be conducted in order to be able to improve the concept furthe.

Special attention needs to be paid to the situation that the ground water level is just below the store. Increased thermal losses in comparison to locations without ground water are expected. Hence, one focus of the monitoring will be the determination of the effect of ground water (flow) on the thermal losses. Ground water level, temperature, flow velocity and direction will be additionally monitored. Three wells will be installed that allow for the continuous determination of ground water velocity, level and temperature. A thermal response test is planed in order to determine the soil properties (thermal conductivity, thermal diffusivity).