Editors Note: Straight off – we’re not fans of gas fireplaces. They can keep you warm but so inefficient they need a TON of gas to do so. Plus, they’re potentially DEADLY if you don’t know how to use one safely, which includes NEVER closing the damper! Here’s why.
LESLIE: Jo in North Carolina has some concerns about a gas fireplace. What can we do for you?
JO: Yeah, I moved into this house about 12 years ago and the gas logs were already here. And I was under the impression that when I operate the gas logs, that I need to have the chimney flue slightly open.
TOM: No, not slightly open; all the way open.
LESLIE: (overlapping voices) Open.
JO: Always open, would you say?
TOM: All the way open. Absolutely. Because you’re burning – you know, you’re burning natural gas; that’s going to convert to carbon monoxide. You’ve got to make sure that vents (ph) up the house; it’s not slightly open, it’s all the way open. And in fact, in some gas log situations where it’s conversion from a wood burner to a gas-burning log, they put a bracket on a damper to prevent you from ever being able to close it because that could be very dangerous.
JO: Oh. Well, she said something about – this neighbor of mine was saying some are vented and some are not vented and …
TOM: That’s true. But you have a standard gas log in a fireplace that used to be a regular fireplace; used to be a wood burner?
TOM: Yeah, an unvented gas fireplace is a manufactured unit – you know, a steel unit – that’s made under very careful controls; and, frankly, even though it is designed to be unvented, we don’t like them.
LESLIE: Mm-hmm. They really should always be vented.
TOM: We would much prefer that they always be vented. But in your case, those gas logs are pretty big burners. Those are usually like 60,000 or 80,000 BTU burners. They use a lot of gas and they need a lot of venting, so make sure you leave the damper open at all times when that’s being used.
JO: Hmm. Oh, OK. Alright.
TOM: Alright? Not the answer you wanted to hear but that’s the answer that’s going to keep you safe, OK?
JO: Yeah. She said it’d be warmer if I just closed the flue but now that I …
TOM: No, it would be warmer and you would be deader. OK?
JO: Yeah. (chuckles) OK.
TOM: Don’t do it.
JO: Alright. Thanks a lot.
TOM: Good luck with that project. Thanks so much for calling us at 1-888-MONEY-PIT.
I have a wood burning fireplace that was converted into a gas burning fireplace.
My damper chain broke and I’m having to use a poker to open and close circular damper. Which is a pain. Do I have to close damper after use?
I live on the coast of Oregon which stays cold to cool/warm. Not sure I want cold air coming down the chimney into the house when not using the fireplace.
Is there an easy way to fix broken chain on circular damper without calling an expensive repair company?
Therese, it sounds like the broken damper is directly above the firebox and I also presume you have a brick fireplace with a clay flue liner. If that’s the case, I’d suggest you remove the original damper completely or there’s a c-clamp style fitting called a damper clamp that can be attached to make sure it never closes inadvertently which could present a carbon monoxide risk. Instead, you should then install a new damper at the top of the chimney flue. These weighted flue liner dampers swing open by default, and are closed by pulling on a stainless steel cable that’s fed down through the chimney to the firebox. Take a look at these dampers on Amazon. Buy the one that fits your flue liner and have it installed by a professional.