Thermaflex 53716000002 Flex Duct R-4.2 16in X 25ft

Product Description

The THERMAFLEX 53716000002 is a 16-inch diameter, 25-foot length insulated flexible air duct rated at R-4.2, designed for low- to medium-pressure HVAC distribution systems. The inner core is constructed from smooth, airtight polyester film laminated over a heavy-gauge, corrosion-resistant steel wire helix. This innercore structure maintains round cross-section under compression and resists kinking during routing. A thick fiberglass insulation blanket wraps the core, and a bi-directional reinforced metallized outer vapor barrier encapsulates the assembly. The outer jacket is engineered to resist unraveling at seams and cuts, making field handling more reliable for installation crews working in tight attic or crawlspace conditions.

This flexible duct is suited for residential and light commercial forced-air HVAC applications. It is commonly installed as branch runout duct connecting supply plenums or trunk lines to diffusers, registers, and grilles. The 16-inch diameter is typical for high-volume supply runs in larger residential systems or commercial rooftop unit distribution. Licensed HVAC technicians and sheet metal contractors are the primary installers. The R-4.2 insulation value meets minimum energy code requirements in many climate zones, making it a standard choice for unconditioned space duct runs such as attics and crawlspaces.

Key Features

• Smooth polyester inner core supports airflow efficiency in low- to medium-pressure systems
• Corrosion-resistant steel wire helix maintains duct shape and resists collapse
• R-4.2 fiberglass insulation blanket reduces thermal loss in unconditioned spaces
• Bi-directional reinforced metallized outer vapor barrier resists moisture infiltration and will not unravel
• Rated for airflow velocities up to 5000 FPM
• Temperature range of -20 degrees F to 250 degrees F supports heating and cooling applications

Compatibility

Designed as an OEM-style flexible duct for use in residential and light commercial forced-air HVAC distribution systems requiring a 16-inch inside diameter branch or trunk runout connection.

Installation Notes

Installation should be performed by a licensed HVAC technician or sheet metal contractor in accordance with SMACNA flexible duct installation standards and applicable local mechanical codes. Power down the air handling unit and verify the system is de-energized before connecting or repositioning duct sections. Avoid sharp bends that reduce the duct's effective cross-section; maintain bend radii per manufacturer and code guidelines to preserve rated airflow performance. Seal all connections with UL 181B-rated mastic or approved metal tape — never use standard cloth duct tape.