Thermaflex 54210000002 Flex Duct 10 in 25 Ft R6

Product Description

The THERMAFLEX 54210000002 is an insulated flexible air duct from the Flex-Vent KP Series, engineered for residential and light commercial HVAC distribution systems. Constructed with a polyester and steel core, it delivers a thermal resistance rating of R6 and a velocity rating of 5,000 feet per minute, making it suitable for high-flow supply and return air applications. The duct measures 10 inches in diameter and 25 feet in length, providing a full run for trunk-to-diffuser connections without mid-run splices. Licensed HVAC technicians and sheet metal contractors are the primary installers of this product.

This flexible duct is used in ducted forced-air systems where rigid ductwork transitions to flexible runs serving ceiling, wall, or floor diffusers. Its operating temperature range of -20 to 250 degrees F accommodates both heating and cooling system airstreams. The low vapor transmission rating of 0.1 perm reduces the risk of condensation within the duct assembly, which is particularly relevant in high-humidity climates and unconditioned attic or crawl space installations. It is produced domestically.

Key Features

• R6 insulation rating reduces heat gain and loss along the duct run
• 5,000 feet per minute velocity rating supports high-CFM supply applications
• 10-inch diameter by 25-foot length provides a full flexible run in a single piece
• Positive pressure rating of 10 inches water gauge and negative rating of 0.5 inches water gauge
• 0.1 perm vapor transmission minimizes condensation risk in humid environments
• Polyester and steel construction balances flexibility with structural integrity

Compatibility

Designed as an OEM-style replacement or new-installation flexible duct for residential and light commercial forced-air HVAC distribution systems using 10-inch round duct connections.

Installation Notes

Installation should be performed by a licensed HVAC technician in accordance with SMACNA flexible duct installation standards and local mechanical codes. Always power down the air handling unit before connecting or disconnecting duct sections, and support the duct at intervals specified by the manufacturer to prevent sagging that reduces airflow. Secure all connections with approved clamps and mastic or listed duct tape rated for flexible duct. Avoid sharp bends or compressions that restrict airflow or degrade the insulation wrap.