Identification of the Hydronic Index Circuit and Dynamic Balancing in Variable-Flow Chilled Water Systems

In multi-story variable-flow chilled water (CHW) networks, improper sensor positioning and misidentification of the system index circuit lead to severe hydraulic starvation at remote terminals or substantial auxiliary pumping energy waste. This paper presents empirical field data from a commercial high-rise facility in the Eastern Province, Saudi Arabia, detailing a systematic step-by-step diagnostic procedure for identifying the true index circuit (AHU-14) and executing dynamic balancing. By relocating the main differential pressure (DP) control sensor to a 2/3 location along the main riser and calibrating Pressure Independent Control Valves (PICVs), design flow was fully restored to starved branches while reducing pump power draw by 24.3% (142 kW to 107.5 kW). All specific corporate and facility identifiers are anonymized per standard academic disclosure protocols.