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Letter: In defense of duct covers
The column on plastic duct covers (“Plastic duct covers not all they’re wrapped up to be,” July 2015 Snips, page 30) presented an interesting view. While there are valid points, there are other considerations.
Duct cleaning is expensive and can rely on the use of soap, chemicals and mechanical means and methods that are in themselves environmentally unfriendly.
This cost can be four to five times the cost of the plastic used to protect the duct. Soap can be used in the shop to clean duct but cleaning with soap after installation can be problematic.
Also certain chemical cleaners will actually de-galvanize the duct, leading to corrosion and other issues. And if lined duct is used, you are limited to mechanical means of cleaning, which are marginally effective on lined ductwork.
Filters are used as part of the process already. Supply fans typically use 100 percent outside air to temper the interior of the building and discharge 100 percent of that air back to the atmosphere. Our company does this on all jobs — Green Globe, Leadership in Energy and Environmental Design and non-certified projects.
When the system is run, the ducts are typically installed and the ducts by themselves maintain positive pressure, which keeps them clean.
Typically, a quality contractor will re-cap the duct at the end of each day during construction so dirt does not enter the duct. Also, much of the time drywall installation starts after the duct systems are installed so the duct acts as its own protection.
There are exceptions, but I would say based on my experience that most duct systems are protected for much of the time.
Ducts do have a residue on them from the raw material supplier and the contractor who makes the duct, which can trap a bit of dirt. So if the ducts were transported without caps, some road and jobsite dirt could be captured and trapped. Chemical cleaning or mechanical cleaning would be required. And once a system is complete, with all the fittings that are normal to a complex duct system, many access holes would have to be cut in the duct with no guarantee that all the duct would be adequately cleaned.
If plastic duct caps were not used, a step of protection would be eliminated, making the ducts dirtier and requiring a much more expensive and potentially environmentally unfriendly process a necessity.
Great discussion. I would be interested in hearing if others have found alternative methods to protect ductwork.
Michael J. Kotubey, President, TD Industries, Dallas