Deterioration of Owens Corning Flex Duct in Air Conditioning or Heating Systems
Defective duct products and materials
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This chapter of "How to Inspect the Central Air Conditioning or Cooling System" describes the
Owens Corning flex duct disintegration as an example of
defective heating or cooling ductwork materials such as Goodman gray flex-duct, and some (not all) Owens Corning Flex-duct products.
This chapter discusses Owens Corning Flex Duct failures with references to product failures by two manufacturers of flexible duct work,
Owens Corning(TM) and Goodman(TM). Neither of these products is currently sold (2006) but both may be found in older homes. Not all
Owens Corning ducts share this defect and disintegration problem.
Air conditioning duct system defects include a remarkably wide range of errors, from failure to supply cool air or failure to even circulate air
in the building, to health hazards such as use of asbestos material in or on duct work, to very dangerous conditions such as drawing heating
equipment combustion gases into the building cooling (or heating) air.
The master document, of which this is a chapter, describes the inspection of residential air conditioning systems (A/C systems) to inform home buyers, owners, and
home inspectors of common cooling system defects.
Asbestos in or on HVAC ducts is a possible hazard for which we provide links to a separate document - see "Asbestos HVAC Ducts" at below left.
OWENS CORNING FLEX DUCT - Deterioration
This generation of Owens Corning™ gray plastic-covered, fiberglass insulated duct material is a defective duct product.
As with the Goodman flex-duct problem described at GOODMAN GRAY FLEXDUCT, in hot attic spaces or where exposed to UV light, the plastic of this Owens Corning flexible air conditioning
duct material disintegrates leaving its fiberglass insulation exposed to also disintegrate, leak, or possibly blow into
the building living space.
When a 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.
Replacement of the heating or air conditioning flexible sections of duct work is required - a significant expense which will be greater if flex-duct needs to be replaced where it passes through inaccessible areas such as finished walls or ceilings. - Thanks to Mark Cramer for this photo.
of Owens Corning gray flex duct disintegrating in a Florida attic.
Notice that not all Owens Corning flex-duct products will fail in this manner
and unless you specifically find evidence of this deterioration, replacement of the flex-duct in a building may not be warranted. Where this duct is found in a building it should be replaced.
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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.
Thanks to Jon Bolton, an ASHI, FABI, and otherwise certified Florida home inspector who provided photos of failing Goodman gray flex duct in a hot attic.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
"Air Conditioning & Refrigeration I & II", BOCES Education, Warren Hilliard (instructor), Poughkeepsie, New York, May - July 1982, [classroom notes from air conditioning and refrigeration maintenance and repair course attended by the website author]
Carson Dunlop, Associates, Toronto, have provided us with (and we recommend)
Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment ($69.00 U.S.).
InspectAPedia® Home & Site Map - Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice: In-depth research & advice on diagnosing, testing, correcting, & preventing building defects & indoor environmental hazards. Unbiased information, no conflicts of interest.
The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems
Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.
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