Fault diagnosis in air-conditioning systems: A multi-step fuzzy model-based approach

The problem of diagnosing faults in air-conditioning systems is of increasi ng importance. A brief review of heating, ventilating and air-conditioning (HVAC) fault diagnosis schemes is given, the key design issues are identifi ed and the advantages of the fuzzy model-based approach are summarised. The way in which the fuzzy fault diagnosis scheme is able to take account of m odelling errors, ambiguous data and sensor bias is explained. A multi-step approach to the fuzzy model-based approach is proposed that makes the resul ts of the diagnosis less ambiguous. A computer simulation study is used to demonstrate that a more precise diagnosis can be obtained using the new sch eme. Experimental results are also presented that show that the proposed sc heme does not generate false alarms when it is used to commission an air-ha ndling unit in a commercial office building.