Adaptive hydronic balancing for heating systems

Hydronic balancing is an essential feature for efficient operating of heating systems. It ensures that each radiator in the system receives the required amount of heating water flow, preventing over- and undersupply. This is achieved by using additional hydronic throttle resistances for consumers with less resistances.

In practice, hydronic balancing is rarely performed, especially in existing buildings. Because in general, the data of this kind of buildings i.e. building envelop, pipe structures etc. are no longer available. Therefore, a proper calculation for hydronic balancing is impossible. An improper balancing will result in inefficient heating systems, high energy costs, and increased greenhouse gas emissions.

An innovative adaptive method for hydronic balancing enables the hydronic resistance at the valve to be automatically adjusted to the current demand, regardless of the system’s current operating state (full load or partial load). Unlike static balancing, the adaptive balancing takes into account factors such as internal and external heat loads , fluctuating ambient temperatures, and individual ventilation behaviour. The settings are made by the position of the valve lift and not by the classical pre-setting on the valve body.

This requires the replacement of conventional thermostatic valves with electronic actuators. During the heating up phase, the valve lift setting is specified as a fixed value (stroke limit) to guarantee needs-based supply for all rooms in the heating system. After the heating up phase, the entire adjustment range is available again. Based on the temperature rises of every room the algorithm calculates stroke limits for the relating valves in the system to be set during the heat up phase.

This adaptive method was developed and investigated in several phases: Software-in-the-Loop (SiL), Hardware-in-the-Loop (HiL) environment with different test stands. Finally, the effectiveness of the method was confirmed in the field tests on different building types, such as multi-family houses and single-family houses. These comprehensive investigations confirmed the reliable functionality of the developed adaptive method for hydronic balancing.