The origin of high return temperatures in district heating substations can be multiple (e.g., heat exchangers, valves, sensors, pumps, etc.). However, the most frequent faults are reported to be problems in the control systems: setting errors, component malfunctions, and substation construction errors, noting that the simplest and cheapest to solve are (luckily) also the most frequent, i.e., control systems with inadequate settings [2].
In view of the above considerations, the first solution to improve the temperature levels in the heating networks is to check the proper functioning of the substations by regular monitoring and checking the frequent sources of error when their performance is not satisfactory. The next step may be a modification in the choice of the substation architecture.
