Abstract
Radiators with improper flow rates are common in today’s hydronic heating systems, which causes undesired temperature variations between thermal zones. Flow rates are set by manually adjustable balancing valves mounted at various locations on the heating system pipes. The conventional procedure for tuning balancing valves is to use settings calculated from a building model based on the construction plan. However, for many zones, those valve settings lead to an unsatisfactory indoor climate, which can be attributed to commonly occurring discrepancies between the construction plan and the actual building. Consequently, this method must be accompanied by manual fine-tuning based on guesswork, which is very time-consuming. In this work, we aim to address these issues with a novel model-based approach involving system identification on operational time series data, including indoor temperature for each thermal zone, central supply temperature, and outdoor temperature. Through an optimal control perspective, we formulate the tuning of valves as an optimization problem informed by identified gray-box models, one for each thermal zone. We demonstrate the method in a case study performed in a residential building in Örebro, Sweden. The results indicate reduced indoor temperature variance after applying valve settings suggested by our method, which is a promising sign of applicability.