Flexduct 640C Flex Air Duct R-4.2 6 Inch 25 Foot Insulated

Product Description

The FLEXDUCT 640C is a pre-insulated flexible air duct designed for residential and light commercial HVAC distribution systems. Built with a ripstop foil outer jacket, this duct delivers R-4.2 thermal insulation performance in a 6-inch diameter configuration and comes in a 25-foot length. The silver foil outer layer resists tearing during handling and installation, reducing the chance of insulation damage before the duct is secured. HVAC technicians and sheet metal installers use this product to connect air handlers, plenums, and branch runs to supply registers where rigid ductwork is impractical or space is limited.

This duct is suited for supply-air branch runs in forced-air heating and cooling systems. The 6-inch diameter is a common branch-run size in residential new construction and retrofit work. The 25-foot continuous length reduces the number of joints needed on longer runs, which helps maintain system static pressure and minimize leakage points. It is appropriate for low-pressure residential HVAC applications and installs in attics, crawlspaces, and conditioned chases.

Key Features

• R-4.2 insulation value reduces heat gain and loss along supply runs
• Ripstop foil outer jacket resists tears and punctures during handling and installation
• 6-inch diameter fits standard residential branch-run collar sizes
• 25-foot length minimizes mid-run joints and associated leakage risk
• Silver foil exterior compatible with standard flex duct straps, saddles, and drawbands

Compatibility

Designed as an OEM-style replacement and new-installation flexible duct for residential and light commercial forced-air HVAC supply systems using 6-inch branch-run fittings.

Installation Notes

Flexible duct is installed by licensed HVAC technicians or sheet metal contractors. Power down the air handler and close the system before cutting into any plenum or existing ductwork. Secure each end with an approved drawband and mastic or UL-listed tape rated for flexible duct connections per local mechanical code requirements. Avoid sharp bends and compression of the inner liner, as both significantly increase system resistance and reduce airflow.

Technical Specifications

• Diameter: 6 inches
• Length: 25 feet
• Insulation R-Value: R-4.2
• Outer Jacket: Ripstop foil, silver
• Package Dimension (L x W x H): 21 inches

Standard Information

• Brand: FLEXDUCT
• Manufacturer Part Number: 640C