Quietflex 18KMR8 Flexible Duct 18 in R-8 Foil Jacket 25 Ft

Product Description

The QUIETFLEX 18KMR8 is an 18-inch diameter flexible duct with R-8 insulation and a foil outer jacket, engineered for large-capacity air distribution in HVAC systems. The R-8 insulation rating delivers significantly reduced thermal loss compared to standard R-4.2 or R-6 flex duct, making it the appropriate choice when energy codes require higher insulation values in unconditioned spaces such as attics, crawlspaces, and mechanical rooms. Each section measures 25 feet in length. Licensed HVAC technicians and sheet metal contractors install this product as part of supply or return air duct systems.

This flex duct is sized for commercial and high-capacity residential HVAC applications where large airflow volumes are required. The 18-inch diameter accommodates high-CFM trunk or branch runs typically found in light commercial builds, large retail spaces, or institutional facilities. It is well suited for installations in unconditioned attic and plenum spaces where energy codes mandate elevated insulation performance. The foil jacket provides a durable vapor barrier and protects the insulation from mechanical damage during installation.

Key Features

• R-8 insulation rating minimizes thermal loss in unconditioned spaces
• 18-inch inner diameter supports high-CFM commercial air distribution
• Foil outer jacket acts as a vapor barrier and protective sleeve
• 25-foot section length reduces the number of joints needed in long runs
• Flexible construction allows routing around obstructions without rigid fittings

Compatibility

Designed as an OEM-style flexible duct section for use in commercial and large residential HVAC supply and return air distribution systems requiring 18-inch diameter flex duct with R-8 insulation.

Installation Notes

Installation should be performed by a licensed HVAC technician in accordance with SMACNA flexible duct installation standards and applicable local mechanical codes. Power down and lock out the air handling unit before connecting or modifying duct runs. Flex duct must be fully extended without sags or sharp bends to maintain rated airflow and insulation performance. Secure all connections with approved straps and mastic or listed duct tape rated for the application.

Technical Specifications

• Inner Diameter: 18 inches
• Insulation R-Value: R-8
• Jacket Type: Foil
• Section Length: 25 feet

Standard Information

• Brand: QUIETFLEX
• Manufacturer Part Number: 18KMR8