Supply Duct Specification


TAG: Double Wall Supply Duct


  1. Factory-built double wall prefabricated supply duct used when supply duct systems are installed in unconditioned space inside and outside the building envelope.
  1. The manufacturer assumes no liability for the use or results of use from this document. Specifications are to be reviewed by the engineer to confirm the requirements of the project and meet Federal, State, and Local codes.
  2. As the manufacturer continues product development, it reserves the right to change design and specifications without notice.
  1. Double wall supply duct complies with ANSI (American National Standards Institute) and SMACNA (Sheet Metal and Air Conditioning Contractors) best practices.
  1. All units shall be provided with the following standard warranties:
    1. Double wall supply duct systems are warranted to be free from defects in material and workmanship, under normal use and service, for a period of 20-years from the date of shipment.
  2. This warranty shall not apply if:
    1. The equipment is not installed by a qualified installer per this installation guide; the operation manual should be kept with the equipment once installation is
    2. The equipment is not installed in accordance with Federal, State, Local codes, and
    3. The equipment design or sizing is not approved per MANUFACTURER’S
    4. The equipment is misused, neglected, or not maintained per the MANUFACTURER’S maintenance instructions.
    5. The equipment is exposed to elevated temperatures due to a fire originating in the building, supply duct, or Rooftop Unit (RTU).
    6. The equipment is not operated within its published
    7. The equipment is operated, tested, or stored in the presence of chlorines, solvents, refrigerant vapors, caustic substances, halogenated compounds, or other conditions that could cause condensation of corrosive materials within or on the
    8. The equipment is substituted or connected with parts not manufactured per Original Equipment Manufacturer.
    9. The invoice is not paid within the terms of the sales
  3. The manufacturer shall not be liable for incidental and consequential losses and damages potentially attributable to malfunctioning equipment. Should any part of the equipment prove to be defective in material or workmanship within the 20-year warranty period, upon examination by the manufacturer, such part will be repaired or replaced by manufacturer at no charge. The buyer shall pay all labor costs incurred in connection with such repair or replacement. Equipment shall not be returned without manufacturer’s prior authorization, and all returned equipment shall be shipped by the buyer, freight prepaid to a destination determined by the manufacturer.


  1. Intended for use with Rooftop Units (RTU’s) or Dedicated Outdoor Air Systems (DOAS) to deliver and diffuse supply air to the space.
  1. Inner duct shall be constructed of .024” thick stainless steel for diameters 5" through 24" and .036” thick stainless steel for diameters 26” through 36”.
  2. Outer duct section wall shall be constructed of stainless steel at a minimum of .024" thickness.
  3. Duct shall include layers of Microlite FSK formaldehyde-free fiberglass insulation between the inner and outer wall to meet specified R value requirements.
  4. Duct sections shall be held together by the means of a formed V clamp. V clamp hardware shall be of the hex-head type with flanged stops and tapered "lead in" threads.
  5. Duct joints shall be sealed with light-duty blended EPDM foam gasket.


  1. Examine areas and conditions for compliance with requirements for installation tolerances and other conditions affecting performance of work.
  2. If unsatisfactory conditions exist, correct conditions prior to installation.
  1. Suitable for use in commercial and industrial space requiring double wall supply duct systems.
  1. Install in accordance with manufacturer's instructions, drawings, written specifications, manufacturer’s installation manual, and all applicable building codes.
  1. Piping installation requirements are specified in other Division 23 Sections. Drawings indicate the general arrangement of piping, fittings, and specialties. Install the duct system to allow service and maintenance.
  2. Duct installation requirements are specified in other Division 23 Sections. Drawings indicate the general arrangement of ducts.