Quietflex 8518 Flexible Air Duct 18 in R8 25 Ft

Product Description

The QUIETFLEX 8518 is an 18-inch diameter, R8-insulated flexible air duct designed for residential and light commercial HVAC distribution systems. The duct features a rip-stop silver polyester vapor barrier jacket over galvanized metal core wire reinforcement, with Johns Manville formaldehyde-free fiberglass insulation rated at R8. It ships in a 25-foot bagged length and is UL 181 Class 1 listed. The oversized core is engineered to slip onto standard collars and register boxes without forcing. Licensed HVAC technicians are the primary installers for supply and return air branch runs.

This flex duct is suited for supply air branch runs in residential forced-air systems as well as light commercial applications. The R8 insulation value meets or exceeds energy code requirements in most jurisdictions, including IECC climate zones that mandate R8 on supply ducts in unconditioned spaces. The silver metallic jacket resists moisture vapor and is packaged in weather-resistant material for job-site storage. This product meets HUD/FHA standards 515.2.1 Paragraph B and NFPA standards 90A and 90B, and is compliant with BOCA and City of Chicago codes as well as most federal, state, and local duct codes.

Key Features

• R8 Johns Manville formaldehyde-free fiberglass insulation for high-performance thermal performance in unconditioned spaces
• Rip-stop silver polyester vapor barrier jacket resists tearing during installation and handling
• Galvanized metal core wire reinforcement maintains round shape under normal static pressure
• Oversized core fits standard HVAC collars and register boxes without modification
• UL 181 Class 1 listed and GREENGUARD Certified insulated construction
• Rated for airflow up to 6000 CFM and temperatures from -20 to 200 degrees F

Compatibility

Designed as an OEM-style replacement and new-installation flex duct for residential and light commercial forced-air HVAC supply and return branch duct systems requiring an 18-inch diameter, R8-insulated flexible duct.

Installation Notes

Installation should be performed by a licensed HVAC technician in accordance with SMACNA guidelines and local mechanical codes. Shut down and lock out the air handler or furnace before connecting or disconnecting any duct sections. Secure each end with a draw band and mastic or UL 181B-listed tape — never use standard cloth duct tape. Avoid compressing or kinking the duct, as reductions in cross-section will significantly increase static pressure and reduce airflow performance.

Technical Specifications

• Diameter: 18 inches
• Length: 25 feet
• R-Value: R8
• Maximum Airflow: 6000 CFM
• Temperature Range: -20 to 200 degrees F
• Jacket Material: Polyester (silver metallic vapor barrier with rip-stop scrim)
• Core Material: Steel (galvanized metal wire)
• Insulation: Johns Manville formaldehyde-free fiberglass
• Color: Silver
• Certifications: UL 181 Class 1, GREENGUARD Certified, ASTM C518
• Standards: NFPA 90A, NFPA 90B, HUD/FHA 515.2.1 Paragraph B

Standard Information

• Brand: QUIETFLEX
• Manufacturer Part Number: 8518