How to Control a Fireplace Damper

The success of burning a comfortably warm, low-smoking fire has to do with how to control a fireplace damper. While the components of the fireplace, including the firebox, the flue, and the damper, must work together, the damper can control how much oxygen reaches the fire and how well it continues to burn.

What kinds of things affect the damper?

The efficiency of the fireplace can be affected by many factors, including:

  • Temperature, both inside and outside the home
  • Wind
  • Type of firewood used
  • Moisture content of the firewood
  • Landscaping around the home.

It’s important to keep the damper fully open when starting any fire. Certain types of firewood, such as hardwoods or damp wood, will create more smoke when lit. If the flue is colder than the air outside the house, it will need time to warm up in order to create the draft necessary to draw the smoke up from the firebox and out through the top of the flue. Wind can affect the damper by forcing air down into the flue and causing the fire to receive gusts of oxygen, which can make the flames flare. Tall trees, in combination with wind, can also affect the damper by causing the wind to swirl around above the flue. This can force the smoke back down the flue, causing a back-draft.

Experimenting with the damper

The best way to become familiar with how much control the damper has over the fire is to conduct the following experiment at a few different times and under different weather conditions.

Step 1 – Light the fire

Choose a time to light a fire. It may be better to wait until few people are home in case the smoke may affect them.

Step 2 – Adjust the damper

Experiment by setting the damper in different positions to see how it affects the fire. More oxygen will make it burn more brightly, and less oxygen will curtail the flames.

Step 3 – Monitor the chimney

Each time the damper is adjusted, check the chimney outside to see if the smoke is exiting the house. If it is windy, check to see if the wind is creating a back-draft.

Step 4 – Check for smoke inside the room

If there is any smoke at all entering the room, it will be necessary to open the damper a bit until the smoke goes up the flue. If there is no smoke and the fire is giving off heat, then the damper has been properly adjusted.

Step 5 – Repeat the experiment at different times

It will be helpful to conduct this experiment a few times. Knowing how the damper will react during different weather conditions will enable greater control over the fire.

Enjoying a roaring fire is one of life’s great pleasures. Proper safety precautions should be taken at all times while using the fireplace, but by understanding how the fireplace damper works, it will be possible to build warm fires that can be kept under control.