Commissioning Underfloor Air Distribution System
- A Case Study and Lessons LearnedPaul Tseng and Scott Nelson
Pressure and smoke testing of under floor air distribution systems has been a difficult, time consuming and many times neglected exercise. Due to unclear performance specifications, misunderstood Owner and Contractor expectations, lack of prep work prior to the event, and time constraints during the actual testing, results of these tests can be inconclusive, with neither the Owner nor respective Contractor sure of the systems integrity.
Prior to testing many questions need to be answered:
• Test with or without carpet?
• What static pressure should be tested to if the specifications state one value and the TAB contractor has determined another?
• What is the allowable leakage rate between floor tiles?
• What is considered construction leakage?
• What are the expected results?
A step by step pressure test was performed on a 23,000 sq. ft. zone with all diffusers and floor cracks completely sealed, then repeated with only the diffusers sealed. The results were compared to determine true floor leakage vs. construction leakage.
Efficient methods of sealing the diffusers and floor were discovered. Measurements of static pressure, CFM, crack spacing and other results lead to tools that will allow better prediction of results in subsequent tests of other facilities.
Through lessons learned, we are able to provide specific and efficient methods of testing, better predictions of expected results, and better direction for including pressure and smoke test protocols in specifications. All in hopes that Owners and Contractors can facilitate a pressure or smoke test that can performed without undue impact on schedule, budget or reliability.
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