How to Install an Insulated Flexible Duct

Connecting to Sheet Metal

• 1

  Measure and mark the needed length of the duct.

• 2

  Cut through the plastic and insulation of the duct with a utility knife or scissors.

• 3

  Cut the wire with wire cutters and pull back the plastic and insulation.

• 4

  Slide at least 1 inch of the center of the flexible duct over the hole on the sheet metal duct. Wrap two layers of duct tape over the joint to seal it, then place a hose clamp over the joint and tighten it.

• 5

  Pull the plastic and insulation back over the wire core and secure it with two wraps of duct tape.

Splicing to Flexible Duct

• 6

  Fold back the plastic and insulation on two pieces of flexible duct.

• 7

  Connect the two pieces of flexible duct with a 4-inch metal sleeve.

• 8

  Wrap duct tape twice around the spot where the ducts connect.

• 9

  Place a hose clamp on each duct where it comes into contact with the metal sleeve and tighten the hose clamps.

• 10

  Pull the plastic and insulation back over the wire core and cover the seam with duct tape, making two passes.