Quietflex 730C Flex Duct R4.2 7 Inches X 25 Feet

Product Description

The QUIETFLEX 730C is a pre-insulated flexible duct designed for air distribution in residential, commercial, and manufactured home HVAC systems. Rated at R4.2, it provides thermal resistance suitable for conditioned-space and short-run applications. This unit measures 7 inches in diameter and comes in a 25-foot length. The duct features a galvanized or bronze metal core with an oversized inner liner sized to fit standard collars and register boxes without modification. Johns Manville insulation is used throughout. Licensed HVAC technicians and sheet metal contractors are the primary installers for this product.

The 730C is suited for residential forced-air systems, light commercial air handling, and manufactured housing applications. Its silver outer jacket is weather-resistant, and the package format is designed for easy jobsite handling. The oversized core eliminates the need for adapters at most collar and register box connections, reducing installation time on new construction and retrofit projects alike. It meets HUD and FHA standards for manufactured housing as well as NFPA 90A and 90B requirements, making it applicable across a broad range of project types.

Key Features

• R4.2 insulation value using Johns Manville insulation material
• 7-inch diameter with oversized core for direct fit on collars and register boxes
• Galvanized or bronze metal core reinforcing for structural integrity
• GREENGUARD certified insulated construction
• UL listed and approved to UL 181
• Meets NFPA 90A and 90B, HUD/FHA standard 515.2.1 paragraph B, and most BOCA, City of Chicago, federal, state, and local codes
• Weather-resistant packaging for jobsite storage

Compatibility

Designed as an OEM-style flexible duct replacement or new-installation component for residential, commercial, and manufactured home forced-air HVAC systems using 7-inch round duct connections.

Installation Notes

Installation should be performed by a licensed HVAC technician or sheet metal contractor in accordance with NFPA 90A, 90B, and applicable local mechanical codes. Shut down the air handling unit and confirm the system is de-energized before connecting or disconnecting flexible duct sections. Secure each end with an approved duct clamp and mastic or UL 181-rated tape — never use standard cloth duct tape. Avoid sharp bends and excess compression of the duct body, as both reduce airflow and effective insulation value.

Technical Specifications

• Diameter: 7 inches
• Length: 25 feet
• Insulation R-Value: R4.2
• Insulation Material: Johns Manville
• Core Reinforcing: Galvanized or bronze metal
• Listing: UL Listed/Approved to UL 181
• Certifications: GREENGUARD, NFPA 90A, NFPA 90B, HUD/FHA 515.2.1 paragraph B
• Available Lengths: 12.5 feet, 25 feet, 50 feet, and custom lengths

Standard Information

• Brand: QUIETFLEX
• Manufacturer Part Number: 730C