The damper is the movable metal plate that opens and closes your flue. When it sticks, warps, rusts, or will not seal, you get everything from smoky rooms to sky-high heating bills. Here are the common damper problems and what to do.
What the damper does
The damper sits at the top of the firebox (a throat damper) or at the top of the flue (a top-sealing damper). Open, it lets smoke and gases escape while you burn; closed, it seals the flue to keep heated or cooled air from escaping up the chimney when the fireplace is not in use.
Common damper problems
- A damper stuck open or closed, often from rust or creosote buildup
- A warped damper that will not seal, letting conditioned air escape
- A rusted damper from water getting into the chimney
- A missing or broken damper handle
- Drafts and odors coming down a poorly sealing damper
Why a bad damper costs you money
A damper that will not close is like leaving a window open year-round — heated air escapes in winter, cooled air escapes in summer, and your energy bills climb. A damper stuck closed is a safety hazard, forcing smoke back into the room if you light a fire.
The fixes
Light rust and creosote can sometimes be cleaned so the damper moves freely again. A warped or badly rusted throat damper often cannot be sealed reliably, and a top-sealing damper — which caps the flue and seals with a gasket — is a common, energy-saving upgrade. An inspection identifies the problem and the best fix.
Damper stuck or drafty?
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Call (708) 432-5330Frequently asked questions
Why is my fireplace damper stuck?
Usually rust or creosote buildup. Water in the chimney rusts the damper, and heavy creosote can gum up the mechanism. Cleaning sometimes frees it; severe cases need repair or replacement.
Should the damper be open or closed?
Fully open whenever you have a fire, and closed when the fireplace is cold and not in use, so heated or cooled air does not escape up the flue.
What is a top-sealing damper?
A damper mounted at the top of the flue that seals with a gasket, closing much more tightly than a traditional throat damper. It doubles as a cap and saves energy.
Can a bad damper raise my energy bills?
Yes. A damper that will not seal lets heated air escape in winter and cooled air in summer, much like leaving a window cracked year-round.
Written by Adam Evans, owner of Chimney Sweep Brothers and a chimney technician with 12 years of experience serving La Grange, IL and the western suburbs.