{"product_id":"thermaflex-53709000002-insulated-flex-duct-9-in-x-25-ft-r-4-2","title":"Thermaflex 53709000002 Insulated Flex Duct 9 in X 25 Ft R-4.2","description":"\u003ch3\u003eProduct Description\u003c\/h3\u003e\u003cp\u003eThe THERMAFLEX 53709000002 is a 9-inch diameter, 25-foot insulated flexible air duct designed for low- to medium-pressure HVAC distribution systems. The KM series innercore is constructed from a smooth polyester film laminated over a heavy-gauge, corrosion-resistant steel wire helix. This design maintains duct shape under normal system pressures while delivering an airtight airflow path. A thick fiberglass insulation blanket surrounds the core, rated at R-4.2, providing thermal resistance to reduce heat gain or loss between the air handler and diffuser. HVAC technicians and sheet metal contractors install this product in residential and light commercial ducted systems.\u003c\/p\u003e\u003cp\u003eThis flexible duct is suited for branch-run applications in forced-air heating and cooling systems, including residential new construction and retrofit installations. It is commonly routed from a main trunk line or plenum to individual supply registers. The 9-inch diameter accommodates higher-volume supply runs typical in larger residential zones or light commercial spaces. The 25-foot coil length reduces the need for mid-run connections on longer branch runs, minimizing potential leakage points.\u003c\/p\u003e\u003ch4\u003eKey Features\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003eR-4.2 fiberglass insulation blanket reduces heat transfer along the duct run\u003c\/li\u003e\n\u003cli\u003eSmooth polyester film innercore supports low-friction airflow in low- to medium-pressure systems\u003c\/li\u003e\n\u003cli\u003eHeavy-gauge, corrosion-resistant steel wire helix maintains duct shape and prevents collapse\u003c\/li\u003e\n\u003cli\u003eBi-directional reinforced metallized outer vapor barrier resists moisture infiltration and will not unravel\u003c\/li\u003e\n\u003cli\u003e25-foot coil length reduces mid-run splices on longer branch applications\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch4\u003eCompatibility\u003c\/h4\u003e\u003cp\u003eDesigned as an OEM-style flexible duct for residential and light commercial forced-air supply distribution systems with 9-inch round duct connections operating at low to medium static pressure.\u003c\/p\u003e\u003ch4\u003eInstallation Notes\u003c\/h4\u003e\u003cp\u003eInstallation should be performed by a licensed HVAC technician or qualified sheet metal contractor in accordance with ACCA Manual D and applicable local mechanical codes. Power down the air handling system at the disconnect or breaker before making duct connections. Avoid sharp bends and keep the duct as fully extended as practical to minimize airflow restriction and condensation risk. Secure both ends with approved draw bands and mastic or listed duct tape rated for flexible duct applications.\u003c\/p\u003e\u003ch4\u003eTechnical Specifications\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDiameter\u003c\/strong\u003e: 9 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLength\u003c\/strong\u003e: 25 feet\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInsulation R-Value\u003c\/strong\u003e: R-4.2\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInsulation Type\u003c\/strong\u003e: Fiberglass\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInnercore Material\u003c\/strong\u003e: Polyester film over steel wire helix\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOuter Jacket\u003c\/strong\u003e: Bi-directional reinforced metallized vapor barrier\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePressure Rating\u003c\/strong\u003e: Low to medium pressure\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch4\u003eStandard Information\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand\u003c\/strong\u003e: THERMAFLEX\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number\u003c\/strong\u003e: 53709000002\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"THERMAFLEX","offers":[{"title":"Default Title","offer_id":51619991978290,"sku":"053709000002","price":120.26,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0270\/4519\/9983\/files\/ba73609c661d3af6eda9ba9ebe4fabd3_99765a60-f80e-4464-b5cb-d9380dc8c807.webp?v=1787338378","url":"https:\/\/voomisupply.com\/products\/thermaflex-53709000002-insulated-flex-duct-9-in-x-25-ft-r-4-2","provider":"Voomi Supply","version":"1.0","type":"link"}