Abstract
Residential heating units (from district heating supply) are often optimized when installed but then not serviced thereafter. A service technician is only called in if there is an observable decrease in comfort level. Even if the unit is maintained regularly the technician only observes the actual values on analog meters – and make decisions based on these observations. It is rarely considered how the units operate seen from a supply side. It is possible to verify the operation of the unit by introducing online measurements at a service job and potential optimizations can be identified and documented. Valuable information about the transport time and cooling in the transmission system can be shared with the supplier at the same time.