Flexduct 840C Flex Air Duct 8 in R-4.2 Silver 25 Ft

Product Description

The FLEXDUCT 840C is an 8-inch diameter flexible air duct with R-4.2 insulation, designed for residential and light commercial HVAC distribution systems. The outer jacket features a silver foil rip-stop construction that resists tearing during installation and helps maintain duct integrity over the service life. Each bag contains a 25-foot length, providing enough run for most branch-duct applications from a plenum or trunk line. Rated at R-4.2, this duct meets common energy code minimums for insulated flexible duct in conditioned and semi-conditioned spaces. HVAC technicians and sheet metal installers are the primary tradespeople who specify and install this product.

This flex duct is suited for branch-run applications in forced-air heating and cooling systems where rigid ductwork is impractical or cost-prohibitive. The 8-inch diameter accommodates moderate airflow volumes typical of residential supply runs serving larger rooms or zones. The silver foil outer jacket is appropriate for attic, crawlspace, and mechanical room installations where the duct may be exposed to incidental contact or must reflect radiant heat loads.

Key Features

• 8-inch diameter inner core for moderate-volume supply branch runs
• R-4.2 insulation value meets common residential energy code requirements for flex duct
• Rip-stop silver foil outer jacket resists tearing and puncture during handling and installation
• 25-foot length per bag reduces field splicing on longer runs
• Foil construction reflects radiant heat, suitable for attic and unconditioned-space installations

Compatibility

Designed as an OEM-style replacement and new-installation flex duct for residential and light commercial forced-air HVAC systems requiring 8-inch diameter insulated flexible duct with a minimum R-4.2 insulation rating.

Installation Notes

Installation should be performed by a licensed HVAC technician in accordance with SMACNA flexible duct installation standards and applicable local mechanical codes. Power down the air handler and close the disconnect before making any duct connections. Minimize bends and avoid compressing the duct core, as sharp bends and compression significantly increase static pressure and reduce airflow. Secure both ends with approved clamps or draw bands and seal with UL 181B-rated mastic or tape.

Technical Specifications

• Diameter: 8 inches
• Length: 25 feet
• Insulation R-Value: R-4.2
• Outer Jacket Color: Silver
• Outer Jacket Type: Rip-stop foil
• Category: Flex Duct

Standard Information

• Brand: FLEXDUCT
• Manufacturer Part Number: 840C