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Beginning here with an example from ATCO™ Rubber Products, we list and describe severe deterioration in the plastic exterior and sometimes plastic interior of flexible HVAC ductwork used in heating and air conditioning systems throughout North America.
We include product names, identification photographs, and suggestions for the detection & repair of leaky, damaged flexible ductwork.
ATCO gray flex duct HVAC ductwork deterioration: this article discusses ATCO™ Rubber Products brand gray flex duct disintegration failures with references to product failures by manufacturers of similar flexible duct work products.
We provide flex duct identification & defect recognition photographs illustrating heat-damaged flex-duct covering materials and we explain the implications on home energy costs when this material is installed in buildings.
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Gray Flex-Duct Failures in HVAC Systems: severe deterioration found
ATCO Rubber Products gray flex-duct deterioration in hot spaces
This article describes ATCO™ brand gray flex duct failures that appear as loss of the gray plastic duct covering due to brittleness that appears to be caused by exposure to heat (such as in a hot attic), with references to product failures by several manufacturers of flexible duct work,
including Alloy Systems™, ATCO™ Rubber Products, Goodman™ flex duct, Owens Corning™ flex duct, Owl™ flex duct.
[Click to enlarge any image]
We believe that none of these defective flex duct products is currently sold but both may be found in older homes. Note: not all
Owens Corning flex duct products share this defect and disintegration problem.
Thanks to Nate Stitzlein for these photos
of ATCO Rubber Products gray flex duct disintegrating in an attic. As he reported, " I inspected a 1989 condo this afternoon and found this duct work in the attic.
Thought you might be interested in the images and the name of the company on the duct work." Mr. Stitzlein is a professional home inspector with Crow Home Inspection, llc in central Ohio and can be contacted at www.crowhome.com
The loss of the protective plastic covering on flex duct poses several concerns including loss of the duct insulation, increased air conditioning system operating costs, and possibly air leaks out (if supply ducts are damaged) or un-wanted attic debris leaks in (if return ducts are damaged), and in-duct condensation in the HVAC system leading to mold and indoor air quality concerns.
These gray ATCO flexduct images have the visual characteristics of thermally-degraded "gray flexduct" failures.
I suspect but don't know, that the reason that we see this failure across multiple flexduct brands may be that everybody bought the same gray plastic duct exterior wrap from a single manufacturer, simply having their own brand and text imprinted on it.
Often there are such common sources across multiple product brands that are not widely known.
This ATCO gray flex duct or "flex duct" air conditioning duct work material is a defective product.
In hot attic spaces or where exposed to UV light, the plastic of this flexible air conditioning
duct material disintegrates leaving its fiberglass insulation exposed to also disintegrate, leak, or possibly blow into
the building living space.
Replacement of the duct work is required - a significant expense, more so where damaged ductwork has been run in side of enclosed building cavities such as ceilings & walls. Where this duct is found in a building it should be replaced. When a heating or air conditioning flex-duct product has lost its exterior plastic covering the effects are these:
The cost of heating or cooling the building is increased due to lost insulation: because the ducts are no longer insulated from the ambient temperature in the attic or crawl space where they are located. For example, an air conditioning duct passing through a hot attic and missing its insulation will be heated by the ambient attic air, delivering warmer air to the living space than is desired.
The cost of heating or cooling the building is increased due to leaks: because damaged ducts are more likely to leak, cooled or warmed air intended for the occupied space may be lost in the attic or crawl space where the damaged HVAC ducts are located.
In addition we might see these two indirect problems developing:
Increased circulation of fiberglass particles from the duct insulation or from building insulation which may be picked up and blown into the building air supply
Mold growth in the HVAC ducts due to loss of insulation and increased in-duct condensation in some circumstances.
Below at Technical Reviewers & References we include Flexible Air Duct Installation Manuals, standards, guidelines, and contact information for several flexible air duct manufacturers as well as access to Flexible Duct Performance & Installation Standards provided by the Air Diffusion Council.
Other Gray Flex-Duct Products Surviving Attic Heat
An example of gray flex duct that is surviving the heat in hot attic spaces includes these CertainTeed Certaflex-G25 Class-1 Air Duct material. Eric Van De Ven, our flex duct detective in the field, contributed these photographs. Mr. Van De Ven explained
It appears this duct work is thicker than the others and wasn't deteriorated. It was installed in 1986 and this attic was at least 130 degrees today.
You will notice in our second photo below) that while the flex duct in this home was not obviously heat-deteriorated, it had been cut or mechanically damaged. We recommend patching minor tears with a plastic or foil duct tape.
Certainteed makes a wide range of building insulation products including the flex-duct above and
List of plastic-covered flexible HVAC duct products that appear to deteriorate in hot spaces like attics
Readers concerned with deteriorating plastic and fiberglass-covered flex duct in buildings should see the several HVAC duct failure reports listed just below at CONTINUE READING .
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In addition to any citations in the article above, a full list is available on request.
Thanks to Nate Stitzlein, a professional home inspector and a member of Crow Home Inspection, llc, in Central Ohio. Website: www.crowhome.com, Tel: 740.862.0454, Email: info@crowhome.com
Thanks to Mark Cramer, Tampa Florida, for assistance in technical review of the "Critical Defects"
section and for the photograph of the deteriorating gray Owens Corning flex duct in a hot attic. Mr. Cramer is a Florida home inspector and
home inspection educator.
Flexduct lawsuit, Richard T.D. Bethea et als, v. Song Hee Hong, et al, filed may 29, 2009, Jackson Tennessee Court of Appeals, dispute involving the contract for sale of a house. A musty odor was associated with mold contaminated flex duct in the building. The ductwork could not be cleaned because of its fragility - an Owl-flex duct product. Sellers (correctly) asserted that the ductwork could not be cleaned. The court finding includes the statement that "OWL FLEX ductwork was uncleanable". The buyers ability to terminate the sales contract was upheld.
"Design & Installation of Residential Flexible Ductwork Systems", Georgia Department of Community Affairs, 60 Executive Park, NE, Atlanta GA 30329
- (404) 679-4940 - (800) 359-4663 [Also see the installation manuals below at JPL] - original source dca.state.ga.us/development/construction codes/publications/1ONE.pdf "1. This information is intended to assist contractors, installers and code officials in the proper design and installation of flexible ductwork systems. The information presented in this document comes primarily from sources in the International Mechanical Code including referenced standards and Georgia Amendments. 2. It is recommended as a guide that HVAC system documentation, including owner’s manuals, manufacturer’s installation instructions and a sketch of the duct system design that details duct size and approximate duct lengths be provided to the building owner or posted on the air handling unit or furnace. (See sample Duct System Design Sketch). Documentation should also include Manual J calculations."
"Flexible Duct Performance & Installation Standards", Air Diffusion Council, 1901 N. Roselle Road, Suite 800, Schaumburg, Illinois 60195, Tel: (847) 706-6750, Fax: (847) 706-6751 - Email: info@flexibleduct.org - www.flexibleduct.org/ - "The ADC has produced the 4th Edition of the Flexible Duct Performance & Installation Standards (a 28-page manual) for use and reference by designers, architects, engineers, contractors, installers and users for evaluating, selecting, specifying and properly installing flexible duct in heating and air conditioning systems. Features covered in depth include: descriptions of typical styles, characteristics and requirements, testing, listing, reporting, certifying, packaging and product marking. Guidelines for proper installation are treated and illustrated in depth, featuring connections, splices and proper support methods for flexible duct. A single and uniform method of making end connections and splices is graphically presented for both non-metallic and metallic with plain ends." The printed manual is available in English only. Downloadable PDF is available in English and Spanish.
Flexduct lawsuit, Richard T.D. Bethea et als, v. Song Hee Hong, et al, filed may 29, 2009, Jackson Tennessee Court of Appeals, dispute involving the contract for sale of a house. A musty odor was associated with mold contaminated flex duct in the building. The ductwork could not be cleaned because of its fragility - an Owl-flex duct product. Sellers (correctly) asserted that the ductwork could not be cleaned. The court finding includes the statement that "OWL FLEX ductwork was uncleanable". The buyers ability to terminate the sales contract was upheld.
Owens Corning Duct Solutions - www.owenscorning.com/ductsolutions/ - provides current HVAC ductwork and duct insulating product descriptions and a dealer locator. Owens Corning Insulating Systems, LLC, One Owens Corning Parkway, Toledo, OH 43659 1-800-GET-PINK™
"Flexible Duct Media Fiberglas™ Insulation, Product Data Sheet", Owens Corning - see owenscorning.com/quietzone/pdfs/QZFlexible_DataSheet.pdf "Owens Corning Flexible Duct Media Insulation is a lightweight, flexible, resilient thermal and acoustical insulation made of
inorganic glass fibers bonded with a thermosetting resin."
"Flexible Duct Performance and Installation Standards", (3rd ed.) – Air Diffusion Council, 1901 N. Roselle Road, Suite 800,
Schaumburg, Illinois 60195,
Tel: (847) 706-6750 -
Fax: (847) 706-6751 email: Email: info@flexibleduct.org
HVAC Duct Construction Standards—Metal and Flexible (1995 ed.) – Sheet Metal and Air Conditioning Contractors’ National Association, Inc. (SMACNA)
International Mechanical Code, 2000 Edition, with 2001, 2004 & 2005 Georgia Amendments
Manual D—Residential Duct Systems – Air Conditioning Contractors of America (ACCA)
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In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: info@carsondunlop.com. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Carson Dunlop Associates provides extensive home inspection education and report writing material. In gratitude we provide links to tsome Carson Dunlop Associates products and services.