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 Nearly 70 percent of homes constructed in the United States have some duct systems in the attic. When ducts leak in the attic on the supply side, valuable conditioned air never makes it into the house. Leaky attic ducts on the return side can pull unwanted unconditioned air into the system. Many homes have duct systems that leak at the rate of 30 percent or more, meaning nearly one-third of the energy used to heat and cool the house is lost. Much of the duct losses in attics occur at the connection between the trunk line and the flex duct take-offs, so a well sealed connection with a single-piece collar will improve the efficiency of the forced air delivery system.
While this connection is made with metal take-off collars typically, an alternative polypropylene product has recently been introduced that promises quicker installation and fewer leaks. This connector includes a double-sided adhesive gasket and nylon draw clips that mechanically hold the take-off in place.The installer removes the gasket paper, presses the connector to the duct board or sheet metal trunk line, and pulls the four one-way locking nylon draw clips. The system installs much faster than metal tab collars, which can take several minutes to bend back the tabs and then seal with mastic and tape. Mastic can be applied to the polypropylene system, but it is not required. These connectors can save time (through speedy installation) and energy (with more secure connections). Polypropylene take-offs also minimize personal injury hazards, since there are no sharp metal edges encountered during installation.
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The system is much quicker to install, reducing installation costs.
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The polypropylene connections provide potential energy savings by reducing the likelihood of loose connections and, therefore, the amount of conditioned air lost.
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Installer safety is increased because there are no metal connections.
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It is easy to convert to the polypropylene systems. All required gaskets and ties are included with the component, which is available in standard sizes. Mastic can be used with this system, but it is not required for strength or leakage protection. Depending on quantity and timing, the manufacturer may be willing to ship product components directly to the job site.
The cost of the collars is nearly equivalent to the more common sheet metal components. However, the total installed cost is estimated to be lower due to lower labor cost.
Savings could be 5 to 10 percent for heating and cooling bills in a typical home with attic-installed ductwork – that could amount to $100 per year in more extreme climates.
The polypropylene take-off is UL approved and is classified as a discrete product under UL2043. The original scope of UL2043 was for electrical components and some code officials need to be updated on its change in scope. To date several jurisdictions including the state of Ohio; Tulsa, OK; Beaumont, TX; Garner, NC; and Horry Count, SC have approved this product for use, though the system has received resistance from Raleigh, NC and Oklahoma City, OK.
None available.
Installation time can be reduced by 50 percent from standard methods. The manufacturer conducted a time study for 10 different installations that saved an average of nearly four minutes per install. For a house with 16 takeoffs, this would reduce the installation time by about one hour.
The polypropylene take-off collar has a lifetime warranty against cracking, rust, and erosion.
There are many benefits to the self-sealing polypropylene take-off system including potential energy savings from the increased tightness of the duct system; economic savings from the reduced labor costs; and the safety benefit of having no sharp edges on the take-off collars. The system may cost a little more than traditional metal products, but this initial cost could be offset by reduced installation time.
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