4" Flexible Duct Class 1 Air Duct, Constructed of 2-layers of Polyester Film 100% Bonded Together.(

Code: FLEX0425
Price: $47.44
Quantity in Basket: None
4” Flexible Ducting 25 Feet Per Box.

Class 1 air duct, constructed of 2-layers of polyester film 100% bonded together.

Construction Features
Fully insulated with thick blanked of fiberglass insulation.
Polyethylene or metalized jacket externally applied.
25 feet Compression packaged for easy handling and storage.
Insulation value R-4.2


Installing flexible duct correctly helps ensure the duct system does its job, without adversely affecting system performance.

Installation Precautions

You should always opt for the minimum length of flexible duct. Any necessary bends should be made with not less than one duct diameter centerline radius. When you do bend the duct, it should extend a few inches beyond the end of a sheet metal connection before you bend it. When you're bending the duct, be careful not to compress it.

Proper Support

It's best to follow the manufacturer's instructions on how far apart duct supports can be, but in their absence, SMACNA says supports shouldn't be more that 5 ft. apart. The maximum sag the SMACNA standard calls for is 1Ú2 in./ft. of spacing between the supports. You can consider the connection to other duct or to equipment as a support point.

Hanger or saddle material in contact with the flexible duct has to be wide enough so it doesn't reduce the internal diameter of the duct when the supported section rests on the hanger or saddle material.

The part of the hanger touching the duct should never be less than 1 in. wide. You can use narrower hanger material in conjunction with a sheet metal saddle that meets this specification. This saddle must cover one-half the circumference of the outside of the flexible duct and fit neatly around the lower half of the duct.

The standard allows factory installed supports that are integral to the duct, as long as the manufacturer's recommended installation procedures are followed. However you support the duct, make sure the supports are adequately attached to the structure.

To avoid tearing the duct's vapor barrier, don't support the entire weight of the flexible duct on any one hanger during installation. Avoid contacting the flexible duct with sharp edges of the hanger material. You can repair damage to the vapor barrier using an approved tape. If you penetrate the interior of the duct, you should either replace that section, or treat the torn area as a connection.

* Order Aluminum Foil Duct Tape Part Number: TPE3101.

Any terminal devices you attach the flexible duct to should have their own support.