flexibleduct.org - [ ADC_FAQs.asp ]

FAQs

What is the difference between Air Ducts and Air Connectors?

What about the thickness of insulation?

What materials are used to hang or support flexible duct?

What is the difference between Air Ducts and Air Connectors?

UL (Underwriters Laboratories), in their 181 Standard for Factory-Made Air Ducts and Air Connectors, defines two categories of flexible "ducts".

The UL Listed Air Duct must pass all of the tests in the UL 181 Standard. Air Ducts are labeled with a square or rectangular shaped label showing their respective listing. There is no limitation on the length of runs when using UL Listed Air Ducts.

The UL Listed Air Connector must pass only a limited number of the UL 181 tests, and is labeled with a round shaped label, which states "for installation in lengths not over 14 feet".

What about the thickness of insulation?

Flex duct comes with three different R-Values (4.2, 6.0, and 8.0). In an attempt to standardize, the flexible duct industry no longer states insulation values in thickness and density. The Air Diffusion Council, an industry organization of manufacturers, certifies R-Values based on insulation only, at installed wall thickness, based on ASTM C-518. Underwriters Laboratories classifies these tested R-Values based on plant inspections. These two third party verifications provide an accurate and reliable method of assuring that you are getting the thermal performance that you require.

What materials are used to hang or support flexible duct?

When hanging or supporting flexible duct, there are a number of different materials which are used regionally. ADC doesn't specify a particular material in our Installation Instructions; however, the Air Diffusion Council do make the following statement: "Hanger or saddle material in contact with the flexible duct shall be of sufficient width to prevent any restriction of the internal diameter of the duct when the weight of the supported section rests on the hanger or saddle material. In no case will the material contacting the flexible duct be less than 1 1/2" (38 mm) wide". As in all cases, local jurisdiction has final say in these matters.