Thermaflex 53707000002 Flex Duct 7 in X 25 Ft R-4.2

Product Description

The THERMAFLEX 53707000002 is a 7-inch diameter, 25-foot length insulated flexible air duct from the KM Flex-Vent product line, rated at R-4.2. The inner core is constructed from a smooth, airtight polyester film laminated over a heavy-gauge, corrosion-resistant steel wire helix. This core supports a thick fiberglass insulation blanket. The outer jacket is a bi-directional reinforced metallized vapor barrier designed to resist unraveling. Rated for velocities up to 5000 FPM and temperatures from -20 degrees F to 250 degrees F, this duct is suited for low- to medium-pressure supply and return air systems. HVAC installers and sheet metal contractors are the primary installers of this product.

This flexible duct is used in residential and light commercial HVAC applications where a field-routable, pre-insulated duct section is required. Typical installations include branch runs from a plenum or trunk line to diffusers and registers in forced-air heating and cooling systems. The 7-inch diameter accommodates moderate airflow branch runs. The duct is compatible with standard 7-inch sheet metal collars, spin-in fittings, and flexible duct connectors commonly used in ductwork systems.

Key Features

• R-4.2 fiberglass insulation blanket reduces thermal loss across branch duct runs
• Smooth polyester inner core minimizes airflow resistance and supports low- to medium-pressure operation
• Corrosion-resistant steel wire helix innercore maintains shape and resists kinking
• Bi-directional reinforced metallized outer vapor barrier resists unraveling and moisture infiltration
• Wide temperature rating of -20 degrees F to 250 degrees F suits both heating and cooling applications
• Maximum air velocity rating of 5000 FPM supports standard forced-air system design

Compatibility

Designed as a standard flexible air duct replacement or new-installation component for residential and light commercial forced-air HVAC systems using 7-inch duct connections.

Installation Notes

Installation should be performed by a qualified HVAC technician or licensed contractor in accordance with SMACNA flexible duct installation standards and local mechanical codes. Power down and lock out the air handling unit before connecting or sealing duct sections. Secure each end with an approved draw band or clamp and seal with UL 181B-listed mastic or tape. Avoid sharp bends and excessive compression of the duct, as both increase static pressure and reduce system efficiency.