Quietflex 4KMR8 Insulated Flex Duct R-8 4 in 25 Ft

Product Description

The QUIETFLEX 4KMR8 is a 4-inch diameter, R-8 insulated flexible duct designed for residential and light commercial HVAC air distribution. At 25 feet per section, it delivers fully lined airflow with a corrosion-resistant steel wire helix core that maintains shape under negative and positive pressure. The outer vapor barrier consists of a fiberglass scrim reinforced metallized film laminate jacket, which limits condensation and heat gain across the duct run. Insulation is made with Owens Corning EcoTouch formaldehyde-free fiberglass, rated at R-8 thermal performance. HVAC installers and sheet metal contractors are the primary trades who handle this product.

This flex duct is suited for supply-air branch runs in forced-air heating and cooling systems. Common applications include attic installations, crawlspace runs, and unconditioned space routing where higher R-value insulation is required to meet energy codes. The R-8 rating makes this duct appropriate for climate zones with stricter duct insulation requirements under IECC or Title 24 standards. It ships in both box and bag packaging configurations depending on the order quantity.

Key Features

• R-8 insulation value for high-performance thermal protection in unconditioned spaces
• Corrosion-resistant steel wire helix maintains duct shape and supports airflow integrity
• Outer vapor barrier jacket uses fiberglass scrim reinforced metallized film laminate
• UL Listed to UL 181 and CUL S110 for use in the US and Canada
• Complies with NFPA 90A and NFPA 90B standards
• GreenGuard Gold Certified for indoor air quality
• Made with Owens Corning EcoTouch formaldehyde-free insulation using 99% natural materials

Compatibility

Designed as an OEM-style flexible duct section for residential and light commercial forced-air HVAC systems requiring 4-inch diameter insulated branch duct with R-8 thermal performance.

Installation Notes

Installation should be performed by a licensed HVAC technician or sheet metal contractor in accordance with SMACNA flexible duct installation guidelines and local mechanical codes. Shut down the air handler and verify the system is de-energized before connecting or modifying duct sections. Support hangers should be spaced per manufacturer and code requirements to prevent sag, which increases static pressure and reduces airflow efficiency. Avoid sharp bends that compress the inner liner, as this restricts airflow and reduces effective R-value at the bend.

Technical Specifications

• Diameter: 4 inches
• Length: 25 feet
• R-Value: R-8
• Listings: UL 181, CUL S110
• Standards Compliance: NFPA 90A, NFPA 90B
• Certification: GreenGuard Gold
• Insulation Material: Owens Corning EcoTouch formaldehyde-free fiberglass
• Vapor Barrier: Fiberglass scrim reinforced metallized film laminate
• Helix Material: Corrosion-resistant steel wire

Standard Information

• Brand: QUIETFLEX
• Manufacturer Part Number: 4KMR8