Optimum performance of radiator space heating systems connected to achive lowets possible district heating return temperature Optimum Performance of Radiator Space Heating Systems Connected to achieve lowest possible district heating return temperature

The cooling of primary water in district heating substations is largely influenced by the existing oversizing of space heating systems and its components. Performed simulations show that it is possible, with measurements of temperatures and energy consumption, to estimate the actual oversizing of the space heating system in a specific building and, from that information, to control the supply temperature in the system for highest possible cooling of primary water at all loads. Full optimization is possible if the indoor air temperature can be measured or estimated with sufficient accuracy. Control of an oversized space heating system using the low circulation flow method, as well as low temperature adjustment, results in approximately 12°C improved cooling of the primary water. Further optimization of a low temperature adjusted system can produce another 3-4°C increased cooling. Even a perfectly sized system can be flow optimized with a gain corresponding to almost 2°C. If a high and a low temperature space heating system is compared, and a flow price is used by the district heating company, there is a significant difference, up to 1 900 €/year for a building with 100 apartments, which reflects a magnitude of possible saving by improving a high temperature system.