P2-1. Rooftop Air Conditioning > Approach

• Demonstrate the extension of a fault detection and diagnosis (FDD) system for rooftop air conditioners to families of manufacturer’s rooftop units.

• Develop methods to detect simultaneous faults.

• Assess the economic benefits of applying the FDD system in California.

• Extend test results from a single rooftop unit to all units within a model family. In addition to measured data, manufacturers' performance ratings at design conditions were used to develop models of expected performance for each unit within the family.
  
• Develop methods to model changes in normal behavior based online measurements from field installations. This is necessary for FDD systems that are added to existing equipment and for situations where maintenance service has changed the fundamental performance of the system under "normal" operating conditions (e.g., installing a new compressor or cleaning the coils). Four quick service restaurants, four K-12 classrooms, and two retail drugstores were field test sites for the project.
  
• FDD methods for handling multiple simultaneously faults were developed. In previous simulation testing, it was shown that the FDD method generally identifies the "worst" fault when two faults occur. After the identified fault is repaired, then the method identifies the second fault. Laboratory testing was performed to verify and further generalize the multi-fault method.

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