Quietflex 12KMR8 Flex Duct 12 in R-8 Insulation 25 Ft

Product Description

The QUIETFLEX 12KMR8 is a foil-jacket flexible HVAC duct designed for installations requiring high thermal resistance. Built with R-8 insulation, it is well suited for use in unconditioned spaces such as attics, crawlspaces, and mechanical rooms where heat gain and heat loss directly impact system efficiency. The 12-inch diameter accommodates high-volume airflow runs typical of larger residential and light commercial trunk-and-branch systems. Each section spans 25 feet, reducing the number of joints needed on longer duct runs. Licensed HVAC technicians and sheet metal contractors are the primary installers of this product.

This flexible duct is used in residential and light commercial forced-air HVAC systems where code or energy efficiency requirements call for R-8 insulation levels. It is commonly installed in unconditioned attic spaces, vented crawlspaces, and service corridors where thermal performance between the air handler and the supply register is critical. The 12-inch size fits main supply runs and large branch takeoffs in systems with higher static pressure requirements and greater airflow demand.

Key Features

• R-8 insulation rating reduces heat transfer in unconditioned spaces
• Foil jacket provides a durable outer barrier suitable for attic and crawlspace environments
• 12-inch inner diameter supports high-volume airflow in larger duct systems
• 25-foot length minimizes the number of connections on extended runs
• Flexible construction allows routing around framing, joists, and obstructions without rigid fittings

Compatibility

Designed as an OEM-style replacement and new-installation flexible duct for residential and light commercial forced-air HVAC systems requiring a 12-inch diameter, R-8 insulated supply or return duct section.

Installation Notes

Installation should be performed by a licensed HVAC technician or sheet metal contractor in accordance with SMACNA flexible duct installation guidelines and applicable local mechanical codes. Power down and lock out the air handling unit before connecting or terminating duct sections. Avoid sharp bends and compression of the duct, as both reduce effective airflow and insulation performance. Secure all connections with approved clamps and mastic or UL 181B-listed tape — never standard cloth duct tape.

Technical Specifications

• Inner Diameter: 12 inches
• Insulation Rating: R-8
• Length: 25 feet
• Jacket Type: Foil

Standard Information

• Brand: QUIETFLEX
• Manufacturer Part Number: 12KMR8