How do I Set a Damper on a Chimney Flue?


A damper is a metal plate that is installed in a chimney to help regulate the flow of gases to a fire. On a woodstove, the damper can be adjusted by a knob that extends to the outside of the flue pipe. Adjusting the damper makes the fire burn hotter and faster, or slower and longer. If a damper is closed too much, smoke may enter the living quarters; if left too far open, the fire will burn quickly and need more fuel added. Homeowners can apply different damper settings to regulate the combustion of their woodstove fires.

Things You'll Need

  • Magnetic flue thermometer
  • Locate the damper control knob on the outside of the chimney's vertical flue pipe, when no fire is burning in the stove. Turn the knob all the way to the right, and then to the left, to determine the closed positions of the damper in the chimney. Feel for the damper touching the inside walls of the chimney; this is the closed position.

  • Open the damper when you build a fire or when you add wood to the stove. Turn the knob perpendicular to the closed position to ensure that the damper is completely open.

  • Close the damper partway after the initial volatile gases have burned off your fuel. Turn the damper knob until you feel the damper get tight in the pipe, then reverse the knob to find a midway point between the open and closed settings.

  • Adjust the damper, according to the type of fuel, to keep an average flue temperature of 500 to 800 degrees Fahrenheit; this allows the most efficient balance between combustion and thermal efficiency. Attach a magnetic flue thermometer to your stove chimney to help determine fire temperatures.

Tips & Warnings

  • Season all wood for one year to prevent creosote buildup in your chimney.
  • Close the damper almost completely when the fire is burning very hot from seasoned pine wood, to slow the burning.
  • Open the damper to accelerate the air flow when adding larger pieces of wood to the fire.
  • Use a variety of woods, since each species burns with its own properties; having different woods will allow you more regulation of the fire.

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  • Photo Credit fire image by Horticulture from
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