How to Install a Flue Damper

Written by sarah davis
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How to Install a Flue Damper
Installing a flue damper can save lots of money. (Jupiterimages/ Images)

Installing a flue damper in your home can save money that would be wasted on an economically insufficient flue. The flue damper is a seal that keeps air on the inside of the house from escaping out of the house through the flue. If the seal is not functioning properly, hot air in the winter and cool air in the summer will flow up and out of the flue. The damper can either be installed into a section of flue before it is positioned in the chimney or in a pre-existing chimney.

Skill level:

Things you need

  • Measuring tape
  • 1 assembled section of stack
  • Marker
  • Drill with 1/4-inch bit
  • Spider Flue Damper with cable, bracket and hardware

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    New Stack Section

  1. 1

    Measure the assembled section of stack using the measuring tape. Make a mark halfway down the section of flue with the marker. Make another mark at the same spot on the opposite side of the stack section.

  2. 2

    Drill a 1/4-inch hole through each one of the markings.

  3. 3

    Insert the flue damper into the stack section. Align the holes on each side of the damper with the holes that were drilled in the stack section.

  4. 4

    Place the flue damper shaft straight through the aligned holes. The curved shank will lock into position in the centre of the stack section.

    Existing Flue Stack

  1. 1

    Remove the chimney cap to access the flue stack.

  2. 2

    Measure the inside diameter of the flue with the measuring tape. Purchase a spider damper that is the same size.

  3. 3

    Insert the spider damper into the flue and lower it until the damper's support tabs rest on the edge of the flue. Drop the cable down into the firebox below. The cable will allow opening and closing of the damper from inside the house.

  4. 4

    Adjust the damper cable to reach where desired. Install the bracket that will hold the cable when not in use.

  5. 5

    Replace the chimney cap.

Tips and warnings

  • When properly installed, the flue damper handle is parallel with the flue damper.
  • You may have to install a new chimney cap with the spider damper, but in most cases, you can use your existing cap.

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