Ideally tuned for installation, calibration exchange and requirements of the measuring instruments. Preparation for measuring capsule heat meter installation. A special single-pipe meter connection is installed in the heating circuit return flow between two ball valves. Dependent on the meter design, the return flow temperature sensor is incorporated as part of the meter or is installed separately in the single-pipe connection. Either a T-piece with an immersion sleeve or a special ball valve for measuring the temperature is installed directly in the medium as a retainer for the return flow temperature sensor.