How Does a Fireplace Damper Work?

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If you’ve ever filled your house with smoke just after starting a roaring fire, then you’ve definitely wondered how a fireplace damper works. Unfortunately, a house full of smoke is a common signal that the damper has not been properly adjusted for fireplace use.

What Is a Fireplace Damper?

Like the fireplace itself, the damper is an exceptionally simple concept. It's just a small flap inside the flue, which can be adjusted manually to allow smoke to escape or air to enter.

Fireplace dampers are typically made of metal or ceramic so they can tolerate the heat of the fire without suffering damage. The damper can be opened and closed through a few different mechanisms, including a latch, a pull chain, or a handle.


Fireplaces are constructed fairly simply. The firebox, where the fire is actually burned, is located inside a room of the house, is surrounded by brick, marble, or is sometimes freestanding, as is the case with a wood stove. The chimney houses the flue, which is just the airway in which the smoke rises from the fireplace and exits through the roof. Conversely, outside air can enter through the flue into the firebox.

Diving even deeper down the rabbit hole, the all important damper is located inside the flue.


Unlike the firebox and the chimney, which only serve a purpose when you've got a roaring fire going, the damper plays an important role when the fireplace is both active and inactive.

When the fireplace is in use, an open damper prevents smoke from filling up your home by giving it a way out through the flue. When there's no fire, keeping the damper shut tight prevents cold outside air from entering the house. This helps create energy efficiency.

Lastly, if you use your damper properly, you can control the intensity of your fire just as well as you would from adding more gas or firewood.

If you alter the amount that the damper is actually opened or closed, you limit the amount of oxygen that can enter the flue and interact with the fire. In addition to a fuel like gas or wood, oxygen is a crucial element to maintaining a fire. So, knowing how to control your damper will give you a huge degree of control over your flames that you may have overlooked until now.


Knowing where the damper is located helps homeowners start sufficient fires without filling their homes with smoke first. When the damper is closer to the firebox, it will take longer for the flue to heat up. When the flue is cold, it won’t conduct the smoke up and out of the home, causing it to flow back into the room. If the damper is located just above the firebox, the best way to warm up the flue is by waving a flame, such as a lighted stick or long cone of paper, underneath the damper to create an air current, that the smoke can follow up the flue once the fire is lit.

Dampers located at the top of the flue will allow the flue to stay closer to room temperature, so it will begin conducting the smoke out of the house sooner. Regardless of the position of the damper, it can be adjusted after the fire is lit to control the supply of oxygen to the fire.

By knowing how to operate the fireplace damper, you can control the heat of the fire, the amount of smoke that gets into the house, and make your house more energy efficient by closing the damper when the fireplace is not in use.