Does the damper get removed or clamped when installing a gas insert?
When we install a gas insert with a stainless liner, the damper is permanently clamped open or removed entirely so the liner passes through and the damper can never close on the vent. Leaving an operable damper on a vented gas appliance is dangerous — a closed damper traps combustion gases in the home. Code requires it be fixed open or gone.
Removed or clamped — either way, it can't close
With a gas insert, the whole point is a sealed vent path: a stainless steel liner runs from the insert up through the damper opening to the top of the chimney. The old throat damper is in the way and, worse, is a hazard if it can still swing shut on a burning gas appliance. So we either remove the damper plate entirely or clamp it permanently in the fully open position and pass the liner through. It's a permanent modification, and it's one the inspector confirms before signing off. The homeowner never operates it again — that's by design, not an oversight.
Why a closable damper is dangerous here
An open wood fireplace lets you close the damper when there's no fire, to stop drafts. A vented gas insert is different: it produces combustion byproducts whenever it runs, and those have to leave through the liner. If a damper could close on it — by accident, by a kid, by a forgotten habit — exhaust and carbon monoxide could back into the room. Fixing the damper permanently open removes that possibility. It's a small step that's absolutely required, and it's one of the details a DIY or unpermitted install tends to miss.
The same logic applies to vented gas logs
With vented gas logs — not an insert — the damper isn't clamped shut, but it does have to be locked open so exhaust always vents up the flue; many installs use a damper clamp for exactly that. Ventless logs are the exception, since they're designed to run with the damper closed. Getting this right is part of a proper, permitted install, and the inspector checks it. If we ever service a unit and find a damper that can still swing on a vented appliance, we fix it on the spot. If you're unsure how your existing setup was left, we'll verify it during service. Call (828) 545-0525.
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Related questions
- Do vented gas logs require the chimney damper to stay open?
- Can a gas insert be installed in my existing masonry fireplace?
- Does a gas fireplace insert need a chimney liner?
- Why does a gas insert need two liners (co-linear venting)?
- Can gas logs be installed in any existing fireplace?
- Can I put a gas fireplace in my bedroom?
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