Validation of a new traceable temperature measurement solution for district heating pipe networks

Real-time measurements of temperature and pressure in District Heating (DH) pipe networks is a challenge due to the very limited access to the pipes that are located underground. However, accurate measurements are invaluable to support future optimized operation- and maintenance strategies. In this study, we validated the temperature measurement of a new solution to DH pit measurement points by comparison to calibrated temperature reference standards and investigated the stability of the applied thermistor type - and alternatives - under DH conditions. The results confirmed that accurate measurements within maximum observed errors of 0.13 °C could be obtained with expanded uncertainties down to ±0.3 °C ( k = 2), given that certain proposed modifications are accommodated. Most importantly, the stability test suggested changing the thermistor type from a currently used epoxy coated model to glass-bead thermistors. Furthermore, the results revealed the characteristic time response when using the specific sensor pocket design and identified the optimal vertical position of the long sensor pocket.