Abstract
Radiators with improperly calibrated flow rates are common in modern hydronic heating systems, often resulting in undesirable temperature variations across thermal zones. Flow rates are typically regulated by manually adjustable balancing valves installed at various points throughout the hydronic system. Traditionally, these valves are configured using calculations based on data from construction plans. However, these valve configuration often give a zone temperature variance, which can be attributed to commonly occurring discrepancies between the construction plan and the actual building. Consequently, manual rebalancing – an iterative and time-consuming process based on practical heuristics – is often required.
This work addresses these challenges through a model-based approach informed by operational sensor data. Through modeling of the pipe network hydraulics and thermal dynamics of each zone, an expression is derived to evaluate the performance of the radiators’ flow rates. Model coefficients are obtained from both the construction plan and through system identification using operational sensor data. This enables evaluation of current system performance and the computation of valve reconfigurations that optimize it. To demonstrate the applicability of the method, a retrospective case study of a rebalancing operation in a Swedish heating system is presented. The analysis indicates that the rebalancing improved the balancing conditions, in line with observed reductions in zone temperature variance. Although the method was not applied during the original rebalancing, the results also suggest that using it could have led to even greater performance improvements.