Fault Detection and Diagnosis Method for VAV Terminal Units

Abstract

This paper proposes two fault detection and diagnosis methods for VAV units without a sensor of supply air volume, and the results of applying these methods to a real building are presented. One method detects faults by applying a statistical method to four values calculated using the room air temperatures and the demand values of VAV damper opening of each unit during a steady state operation period. From the results of case studies, the method can reduce the number of units to be checked as faulty ones down to 12% of the total number and all the units that really have a fault are included in this group. The other method judges the faults by applying dynamic system analysis to the operational data when the VAV system starts up. From the result of the case studies, the method can reduce the number of units down to 30%, among which five units actually have a fault and only one faulty unit was not included in this group. Both methods can reduce time and cost for commissioning of VAV units significantly by the help of BEMS.