Resolving Duct Leakage Claims PDF

Reports a study of the performance of eight exhaust systems of a large medical centre in Tennessee. The mechanical contractor of the project initiated the study when confronted with a claim of unacceptable deficiencies in all building exhaust systems. These systems were reportedly exhausting 32% to 43% less than design airflow as a consequence of excessive leakage in the duct system. Discusses the original test and balancing (TAB) procedures. Describes the procedures used in the follow-on study in some detail. Finds that the claims of excessive leakage as reported in the TAB report were false. The flow hood used by the test crew and the hood provided by the independent investigator were measuring incorrectly. Recommends that testing and balancing personnel should question test data that is grossly mismatched.