Flexduct 40SERIESBAG Flex Air Duct 4 in X 25 Ft R-4.2

Product Description

The FLEXDUCT 40SERIESBAG is a 4-inch diameter, 25-foot flexible air duct designed for residential and light commercial HVAC distribution systems. The duct features a rip-stop silver foil outer jacket that resists tears during handling and installation, paired with R-4.2 fiberglass insulation to limit conductive heat loss and condensation on the duct exterior. This product is used in forced-air heating and cooling systems to connect branch runouts from a plenum or trunk line to registers and diffusers. Installation is performed by licensed HVAC technicians or sheet metal contractors.

This flex duct is suited for residential forced-air systems where flexible runouts are required to reach registers in confined or angled spaces. The 25-foot length accommodates typical branch runs without the need for additional couplings. The silver foil outer jacket meets standard requirements for reflective vapor barriers in insulated flexible duct assemblies. It is appropriate for supply and return air applications within the rated temperature and pressure limits of the product class.

Key Features

• 4-inch inner diameter for standard residential branch runout sizing
• 25-foot length reduces the need for mid-run couplings
• R-4.2 fiberglass insulation limits heat gain and loss along the duct run
• Rip-stop silver foil outer jacket resists puncture and tearing during installation
• Flexible construction allows routing around framing, joists, and obstructions

Compatibility

Designed as an OEM-style replacement and standard-fit flexible duct for residential and light commercial forced-air HVAC systems requiring 4-inch insulated flex duct branch runouts.

Installation Notes

Flexible duct installation should be performed by a qualified HVAC technician in accordance with ACCA Manual D and applicable local mechanical codes. Support the duct at intervals no greater than those specified by code to prevent sagging, which reduces airflow and system efficiency. Secure each end with an approved clamp and mastic or code-approved tape rated for duct use — never use standard cloth-backed tape. Minimize sharp bends and compression; a compressed or sharply bent flex duct significantly increases static pressure drop across the run.

Technical Specifications

• Inner Diameter: 4 inches
• Length: 25 feet
• Insulation R-Value: R-4.2
• Outer Jacket: Rip-stop silver foil
• Package Dimensions: 4.5 inches

Standard Information

• Brand: FLEXDUCT
• Manufacturer Part Number: 40SERIESBAG