Insulated Flex Duct R8 – 4″ to 20″ x 25 ft Aluminum Foil Flexible Air Duct for HVAC

Product Overview

An R8 insulated flexible duct, 25 ft long, available in twelve diameters from 4 inch to 20 inch. With a thicker insulation blanket than R6, it holds supply-air temperature over longer runs and stands up to bigger temperature swings between the duct and the surrounding air.

Built from thickened aluminum foil over a high-density fiberglass insulation layer, with a high-strength elastic steel spiral wire running through the core. It bends to any angle without a hard elbow, and the aluminum is self-sustaining — once you shape it, it stays put instead of springing back.

R8 vs R6

R8 is the higher insulation grade. Choose R8 when the run passes through an unconditioned attic, crawlspace or exposed exterior space, or where the temperature difference between the supply air and the surrounding air is large — a thicker blanket means less heat gain in summer, less heat loss in winter, and a much lower risk of condensation forming on the jacket.

Pick Your Diameter

Use the selector above to choose the diameter that matches your run. All sizes are 25 ft long and R8 rated — only the diameter changes.

Specifications

Key Features

• R8 insulation — thicker blanket than R6, for runs through hot attics and cold crawlspaces
• Condensation control — keeps the jacket temperature above dew point, so no sweating and no dripping into the ceiling below
• Less energy loss — supply air arrives closer to the temperature it left the air handler
• Thickened aluminum foil — flame resistant, acid and alkali resistant, built for permanent installs
• High-density fiberglass wool — high thermal resistance and corrosion resistance; the safest class of insulation material
• High-strength steel spiral wire — bends freely, self-sustaining, does not retract after installation
• Cuts noise by up to 85% — the lofted fiberglass structure absorbs sound as air moves through
• Keeps its shape — stays round and smooth, lowering air resistance and static pressure loss
• No hard elbows needed — bends around joists, studs and existing services
• Ships compressed — full 25 ft pulls out of a compact box in seconds

Applications

• Central air conditioning and HVAC supply and return systems
• Fresh air ventilation systems
• Mechanical equipment exhaust and recovery systems
• Long runs through unconditioned attics, crawlspaces and exterior chases
• Any high, medium or low pressure ventilation run carrying non-corrosive gas

Installation Tips

• Pull the duct out to full 25 ft — a compressed run chokes airflow and raises static pressure
• Keep runs as straight and short as possible; every bend costs you CFM
• Support the duct every 4 ft with strap or hanger, and never let it sag between supports
• R8 is thicker than R6 — check clearance before pulling it through tight framing
• Slide the inner core over the fitting, then fold the insulation and jacket back over it
• Clamp the inner core and seal with mastic or foil tape — do not rely on the clamp alone

Note

Rated for ventilation systems carrying non-corrosive gas. Not for use with corrosive fumes.