Thermaflex 52318000001 Flex Air Duct 18in X 25ft R8 UL181

Product Description

The THERMAFLEX 52318000001 is a thermally insulated, fully lined flexible air duct rated R8 and listed to UL 181 Class 1 standards. Measuring 18 inches in diameter and supplied in a 25-foot length, it is designed for low to medium pressure cooling and heating HVAC applications. The smooth inner liner promotes efficient airflow, while the ample insulation layer and tough outer vapor barrier deliver thermal performance and a double air seal. Licensed HVAC technicians use this duct in both new construction and retrofit work where rigid fabricated ductwork is impractical or cost-prohibitive.

This flexible air duct is suited for residential and light commercial HVAC systems in both supply and return configurations. Its flexibility allows routing around structural obstacles and correcting misalignment between system components without costly custom fittings. It is also well-suited for system extensions and zone modifications. Compliance with NFPA standards permits installation lengths beyond the 14-foot limitation that applies to flexible connectors, giving installers more layout options in complex applications.

Key Features

• UL 181 Class 1 listed flexible air duct for verified fire and safety compliance
• R8 thermal insulation rating for low heat loss and high system efficiency
• Smooth inner liner reduces airflow resistance in supply and return runs
• Tough outer vapor barrier provides a double air seal against moisture infiltration
• NFPA-compliant construction allows runs longer than 14 feet without connector limitations
• Suitable for new construction and retrofit installations, including zone extensions

Compatibility

Designed as an OEM-style replacement and new-installation flexible duct for low to medium pressure residential and light commercial HVAC supply and return duct systems requiring an 18-inch diameter, R8-insulated, UL 181 Class 1 listed product.

Installation Notes

Installation should be performed by a licensed HVAC technician in accordance with local mechanical codes and NFPA duct installation guidelines. Power down and lock out the air handling unit before connecting or disconnecting ductwork. Avoid sharp bends or kinks that restrict airflow and compromise the insulation jacket. Secure all connections with listed straps or clamps and seal with UL 181-listed mastic or tape as required by the applicable code.