Mueller Streamline 180690 Flex Duct 20 in R-4.2 25 Ft

Product Description

The MUELLER STREAMLINE 180690 is a large-diameter commercial flexible duct designed for high-volume HVAC air distribution in commercial buildings. It features an R-4.2 insulation value and a metalized jacket with a metalized inner core, providing durability and thermal performance in demanding mechanical room and plenum environments. At 20 inches in diameter and 25 feet in length, this flex duct accommodates high-capacity airflow runs where rigid duct installation is impractical. Licensed HVAC technicians and sheet metal contractors install this product in commercial mechanical systems requiring both flexibility and reliable insulation performance.

This flex duct is suited for commercial HVAC applications including large rooftop unit distribution systems, air handling unit supply and return runs, and ceiling plenum routing where routing flexibility is required. The 20-inch diameter supports trunk-line and high-volume branch applications in commercial construction and retrofit projects. Its metalized jacket and core construction make it appropriate for mechanical rooms and exposed ceiling spaces where durability and vapor resistance matter.

Key Features

• 20-inch diameter accommodates high-volume commercial airflow distribution
• R-4.2 insulation value limits thermal loss along the duct run
• Metalized jacket and metalized inner core provide durability and vapor resistance
• 25-foot length reduces the number of joints needed on longer runs
• Flexible construction allows routing around structural and mechanical obstructions

Compatibility

Designed as an OEM-style replacement and new-installation flexible duct for commercial HVAC air distribution systems requiring a 20-inch round flexible duct connection.

Installation Notes

Installation of large-diameter commercial flex duct should be performed by a licensed HVAC technician or qualified sheet metal contractor in accordance with SMACNA flexible duct installation guidelines and applicable local mechanical codes. Support the duct at intervals consistent with code requirements to prevent sagging, which reduces airflow and increases static pressure drop. Secure all connections to collars and fittings with approved mechanical fasteners and UL 181-rated tape or mastic before powering the air handling system. Avoid compressing or over-bending the duct, as this significantly reduces airflow performance.

Technical Specifications

• Diameter: 20 inches
• Length: 25 feet
• Insulation R-Value: R-4.2
• Jacket Type: Metalized
• Core Type: Metalized

Standard Information

• Brand: MUELLER STREAMLINE
• Manufacturer Part Number: 180690