It’s important to know how to set your fireplace damper when lighting a fire. A properly set damper means the difference between a bright, chill-chasing fire and a room full of smoke. The damper is a flap inside the flue that works to control or stop the flow of air between the firebox and the top of the flue.
Close Only When Fireplace is Not in Use
The only time the damper should stay completely closed is when the fireplace is not being used. While closed, the damper keeps cold air from being blown down into the room through the flue.
Open Damper When Preparing Fire
During the preparation to start a fire, the damper should be completely opened. Failure to open the damper will result in difficulty getting the flame to spread and smoke flooding the room.
The location of the damper affects how the fire should be started. A damper that is closer to the firebox will stay warmer, even closer to room temperature, and will not need to be warmed up prior to lighting the fire. The current to draw the smoke up the flue will form easily.
When the damper is located higher up inside the flue, more toward the roof, it will need to be warmed before starting the fire. This is easily done. Using a piece of wood or several sheets of newspaper rolled into a cone, light the end, then wave the flame slowly underneath the flue for five or ten minutes. When the smoke starts to flow up into the flue, the damper is ready for the fire.
Some factors may affect the warming of the flue. If it is very windy and cold air is blowing into the firebox, the damper may need to be closed slightly to control that air flow. Similarly, if the fire is having a hard time spreading to the other logs; it may be necessary to adjust the damper depending on how the flame responds. The flame may need more or less oxygen. If the wind is strong, continued adjustment of the damper may be necessary to control the flames.
Closing the Damper After a Fire
The damper remains either completely or at least partly open during the burning of the fire. While the fire is going out, and the embers are still smoldering, it is important to continue to keep the damper open. Smoke is still being emitted from those embers and can flow up the flue as long as the damper is open. Closing the damper will result in smoke flowing into the room.
The damper should only be closed after the fire is completely out, which may take up to another full day for the embers to go cold. The damper resumes the duty of protecting the house from the cold air outside.
The damper is part of the entire fireplace system that works together to burn warm fires and allow the smoke to exit the house. The damper must be in the correct position, always open to some degree, while a fire is being burned.