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March 2004
A first generation rigid-plastic ductwork system in a newly constructed home. (Credit: Steven Winter Associates featured in Vol. 7, no. 5 issue of CARB News, November 2003)
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Using rigid-plastic ductwork could be a good way to solve the problem of leaky ducts. Plastic ducts—also known as thermoformed ductwork—feature tight joints, rounded bends, and smooth inner surfaces. These characteristics could virtually eliminate leaks and reduce friction losses.
With a Small Business Innovation Research (SBIR) grant from DOE, Steven Winter Associates (SWA), a DOE Building America partner, recently installed a first-generation rigid-plastic ductwork system in a new home in Georgia to test the product's performance. The local HVAC contractor was Meadows Heating and Air, Inc., and the ducts were manufactured in prefabricated parts by ATS Duct Systems of California. Working with its Building America Consortium for Advanced Residential Buildings (CARB) builder partner—Outlook Construction of Cartersville, Georgia—SWA scheduled performance tests for early 2004.
The aim is to come up with a residential duct system that is not only free of leaks but is also cost-effective and easy to install. According to SWA, early evaluations indicate that plastic ducts provide significant benefits when compared with conventional sheet metal, flex duct, and ductboard systems:
- Rigid-plastic ducts are virtually leak-free because they have fewer joints and the solvent bonding process is likely to produce a leak free joint.
- Their smooth interior surfaces and curved take-offs and turns result in lower friction losses in comparison to conventional systems; this means that smaller ducts could perform as well as larger conventional ones, which also reduces material and operating costs.
- The ducts can be prefabricated to reduce the amount of effort and time required for installation on site.
- They can be cleaned easily, alleviating health concerns about accumulations of dirt and mold.
Outlook Construction has actively participated in this research. Meadows Heating and Air Conditioning, the mechanical contractor used by Outlook for standard installations, reacted very positively to the new system. So did local inspectors at the site during the installation.
Originally designed for highly corrosive exhaust systems, the ATS prefabricated products are UL 181-listed and have a fireproof coating. As part of the demonstration, Bryant Company provided an upgraded FV4 variable-speed air-handling unit. Fantech Iris dampers were installed to help balance and test the system. The plastic ducts were insulated with a polyurethane spray foam.
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