Strategy for low-temperature operation of radiator systems using data from existing digital heat cost allocators

The low-temperature operation of existing radiator systems connected to district heating is hindered by various factors, including non-ideal local control by users. The use of only a few of the available radiators to provide the necessary thermal comfort in an apartment is a common example. This requires a higher supply temperature and results in a high return temperature. This study investigated the potential of minimising the supply temperature of the radiator system to stimulate the use of all the available radiators in each apartment. Data from existing electronic heat cost allocators were used to detect the number of radiators not being used at any given time. A thermal/hydraulic model of the radiator system of a building was created to calculate the minimum supply temperature required according to the maximum pump operation. Energy-weighted average supply and return temperatures of 44 °C and 30 °C, respectively, could be achieved when all the radiators were used. The investigation showed that under the minimum supply temperature and a sufficient hydraulic balance, the required heat could only be delivered if all the available radiators were used. A good hydraulic balance could be secured by appropriately setting the balancing valves in each riser.