Just spent a whole day on a blocked flue in a 1970s ranch house.

The damper was seized solid with creosote, took me 8 hours to finally get it free. Anyone have a better method than a torch and a big pry bar for that?

4 comments

4 Comments

logan6582mo ago

Honestly, @vera195's acetone trick sounds way smarter than my usual brute force. Heard a heat gun can work better than a torch too, less chance of cracking the old metal.

vera1952mo ago

My old boss swore by a mix of half acetone and half automatic transmission fluid to soak it. Let that sit for a day before you even touch a torch. Did you try tapping the hinge pin with a hammer and a small punch first? Sometimes that shock breaks the grip without needing to bend everything.

leewalker2mo ago

Just a heads up, a heat gun can still get hot enough to mess up the temper on some old steel. Seen it happen.

brianreed9d ago

That "messing up the temper" thing @leewalker mentioned is a real concern with older dampers. One thing nobody's brought up yet: sometimes that freeze is actually from the cast iron expanding against the brick over time, not just rust. I've had luck on a couple by pouring white vinegar down the gap around the damper plate and letting it sit overnight. The acid eats into the mineral deposits without harming the metal, then you can often work it loose with way less force.

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