A district-heating network acts like a heat-storage device. This means that the heat load at the district-heating plant is determined not soley by the substations' heat demand. In the model used, the flow demands and return temperatures of two-stage substations are calculated for ideal static conditions. The circulation time of the primary water is calculated from flows and pipe dimensions under ideal conditions, where heat losses are neglected. The results obtained shows that the commonly used strategy for the supply temperature (i.e. increasing with decreasing outdoor temperature) in combination with the net structure yields amplified variations of the heat load compared with the actual demands of the attached consumers. It is also shown that from a more appropriate choice of supply temperature, the variations of the heat load may be reduced
