Quietflex 1865 Uv-inhibited Flex Duct R8 18 in 25 Ft

Product Description

The QUIETFLEX 1865 is a UV-inhibited flexible duct designed for residential and light commercial HVAC air distribution systems. Constructed from a fiberglass and polyester composite, this flex duct delivers an R8 insulation value, helping to minimize heat loss and gain in unconditioned spaces such as attics and crawlspaces. At 18 inches in diameter and 25 feet in length, it suits larger trunk-to-register runs where volume airflow and low static pressure drop are priorities. The UV-inhibited outer jacket adds durability in exposed installation environments. Licensed HVAC technicians and sheet metal contractors are the primary installers of this product.

This flexible duct is suited for supply air applications in forced-air systems where a pre-insulated, large-diameter duct run is needed. The 10 in-WC positive and 0.5 in-WC negative pressure ratings make it compatible with typical residential and light commercial air handler outputs. Common install scenarios include attic plenum-to-diffuser runs and equipment room branch takeoffs. The black outer jacket is appropriate for attic installations with incidental UV exposure. No specific model or system compatibility data was provided beyond pressure and temperature parameters.

Key Features

• R8 insulation value reduces heat transfer in unconditioned spaces
• UV-inhibited outer jacket suitable for attic and exposed installations
• 10 in-WC positive pressure rating handles standard forced-air system outputs
• 18 inch diameter supports high-volume airflow in large branch or trunk runs
• Continuous operating range of -20 to 180 degrees F covers full residential HVAC service conditions
• Fiberglass and polyester construction provides insulation integrity and flexibility during routing

Compatibility

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

Installation Notes

Installation should be performed by a licensed HVAC technician in accordance with SMACNA flexible duct installation standards and local mechanical codes. Power down the air handler and verify zero airflow before cutting or connecting duct sections. Avoid sharp bends that exceed the manufacturer minimum bend radius, as excessive compression or kinking reduces airflow and effective R-value. Secure both the inner liner and outer jacket to fittings using approved clamps and mastic or UL 181B-listed tape.

Technical Specifications

• Diameter: 18 inches
• Length: 25 feet
• R-Value: R8
• Positive Pressure Rating: 10 in-WC
• Negative Pressure Rating: 0.5 in-WC
• Continuous Temperature Rating: -20 to 180 degrees F
• Intermittent Temperature Rating: -20 to 200 degrees F
• Material: Fiberglass/Polyester
• Color: Black

Standard Information

• Brand: QUIETFLEX
• Manufacturer Part Number: 1865