Installation of a Control Damper in a Fiberglass Duct

Fiberglass Ductwork

• Fiberglass ductwork is a relatively new phenomenon. This type of ductwork comes in square panels. To assemble, the user cuts along the side of the panel with a special knife and a straightedge. The knife forms a channel that allows you to fold the fiberglass over on itself to a 90-degree angle. Enough of the fiberglass is left on the back side of the cut so that the duct has a built-in hinge.

Control Dampers

• Control dampers restrict air flow through the duct channel. These can be controlled by electrical, where they connect to a centralized switch, or by mechanical means, where the user turns a lever connected to the damper to shut it. Dampers also come in various sizes and insulation depths depending on the amount of temperature that they will control.

Damper Connection

• Fiberglass dampers fit onto the ends of duct channels by means of plastic collars. You need to drill holes through the ductwork so that you can insert nylon retention screws to hold the damper. Do not use duct tape for these types of connections as it will dry out over time and damage the integrity of the damper connection.

Damper Installation

• Make sure that you cut power to the electrical system at the breaker before attaching the duct. Clean the ductwork thoroughly, if installing the damper in pre-existing ductwork. If you are assembling the ductwork for the damper, wear safety goggles and a mask to prevent breathing in the fiberglass particles. Fit the damper to the ductwork and use a pencil to mark the side of the duct where you will attach the retention bolts. Remove the ductwork and drill the holes. Insert the bolts from the inside of the duct with the threads pointing outward. Slip the damper over the end of the duct and lock it into place on the bolts. Secure the bolts with the plastic retention nuts. Connect the damper to the electrical system, if needed.