Flexduct 420C Flex Air Duct 4in X 25ft R-4.2 Fiberglass

Product Description

The FLEXDUCT 420C is a UV-inhibited fiberglass flexible air duct rated at R-4.2, designed for low-pressure residential and light commercial HVAC distribution systems. This 4-inch diameter duct ships in a 25-foot bag and provides thermal insulation along the full duct run, reducing heat gain and loss between the air handler and the supply register. The UV-inhibited outer jacket resists degradation in attic environments where sunlight exposure is common. Licensed HVAC technicians install this duct as part of new construction or retrofit air distribution systems.

The FLEXDUCT 420C is suited for residential forced-air systems where flexible duct runs connect supply plenums or trunks to ceiling or floor registers. The 4-inch diameter is a common size for individual supply branch runs serving smaller rooms or zones. This duct is appropriate for attic, crawlspace, and conditioned-space installations where a flexible, insulated branch duct is required. No specific model compatibility data was provided by the manufacturer for this SKU.

Key Features

• R-4.2 fiberglass insulation rating reduces thermal loss along duct runs
• UV-inhibited outer jacket extends service life in attic and exposed installations
• 4-inch diameter fits standard branch-run collars and boots
• 25-foot length per bag covers typical residential branch run distances
• Flexible construction allows routing around joists, trusses, and obstructions

Compatibility

Designed as an OEM-style replacement or new-construction flexible duct for residential and light commercial forced-air HVAC distribution systems requiring a 4-inch insulated branch duct.

Installation Notes

Installation should be performed by a licensed HVAC technician following local mechanical codes and ACCA Manual D duct design guidelines. Power down the air handler and close the system before making duct connections. Secure each end with an approved draw band and mastic or listed duct tape rated for HVAC use. Avoid sharp bends that reduce the duct's effective diameter and restrict airflow.

Technical Specifications

• Diameter: 4 inches
• Length: 25 feet
• Insulation Rating: R-4.2
• Insulation Type: Fiberglass
• Outer Jacket: UV-inhibited
• Package Dimensions (LxWxH): 21.5 inches

Standard Information

• Brand: FLEXDUCT
• Manufacturer Part Number: 420C