A newly developed procedure--resistance coefficient region contraction (RC 2 )--for hydraulic process fault diagnosis and parameter identification in district heating (DH) networks is discussed in this paper. First, the basic principle of the approach is presented. Then, the method to establish and modify the S (flow resistance coefficient) region, W, is introduced in detail. A special geometrical calculation procedure has been developed for the procedure. Further analysis for detecting and diagnosing the fault is illustrated. Finally, the key to increasing the sensitivity and reliability of the procedure is discussed and a numerical example is given. The method now has been applied in three urban heating systems in China. The past several years of operation shows that it works well.

Units: SI