HVAC Procedure and Performance Guide

TASK: Install branch duct (flexible).

Training for this procedure can be found in these courses:

                         103 – Basic Sheet Metal  and  205 – HVACR High Efficiency Ventilation


Flexible branch duct must be installed according to manufacturer’s specifications, job specifications and codes.  Duct must be tight, must not leak and must not collapse in bends.  Applicable safety procedures must be followed.


  1. Review manufacturer’s specifications and job specifications.
  2. Collect tools, equipment and materials.
  3. Put on safety and protective equipment and apparel.
  4. Determine duct size and routing from specifications.
  5. Prepare duct penetration and register openings.
  6. Install metal damper section on takeoff if necessary.
  7. Connect flexible duct to damper section or takeoff.
  8. Route and support duct to terminal point.
    • Pull duct tight.
    • Install metal fittings in bends if necessary to prevent duct collapse.
    • Make duct connections with metal sleeves and flexible duct clamps.
  9.  Connect stack head, register box or register boot.
  10. Insulate duct if applicable.
  11. Remove safety and protective equipment and apparel.
  12. Gather tools, equipment and leftover materials and leave work site clean.