Fireplace Flue: Open or Closed When Not in Use?

Updated on November 19, 2011
R.D. asks from Richmond, VA
19 answers

My husband, who is a plethora of HVAC knowledge, leaves the flue open ALL THE TIME. Drives me nuts because I say, when not in use, it should be closed to prevent the escape of heat... you know, heat rises and all that. Our house is old, so the heating vents run along the floor boards.

SO, when not in use (like no actual fire in the fireplace), should the flue be opened or closed?

Even if it saves me PENNIES, I say it's worth closing...

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So What Happened?

His reasoning is that it wouldn't make a difference because we do not have double hung storm windows. That may be true, but I'm not trying to encourage heat escape through the chimney here.

In short, he's too lazy to open/close it as needed, and I can't figure the damn thing out because it's jurassic, or I'd do it myself!!

Featured Answers

C.O.

answers from Washington DC on

CLOSED!!! Leaving it open allows bugs, spiders, animals and COLD AIR!!!!

It should ONLY be open when you have a fire and the fire is out completely.

HVAC knowledge doesn't mean fireplace knowledge. CLOSED.

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M.M.

answers from Lake Charles on

My mom and dad leave theirs open all winter but they have these doors on the fireplace that seal it off, if it was just an open fireplace I'd say keep it closed because I can remember falling asleep with the fireplace going and those doors open and waking up to a freezing cold living room.. I'd think it'd save more than pennies, any chance you can learn to open and close it? I know my mom was the one that always did it.

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J.T.

answers from Chicago on

Why does he with his HVAC knowledge say to leave it open? I've never heard of such!

The other day, I got down on the floor in the living room to get the ball from under the couch the silly dog just had to have. It was freezing down there. Why? Because my husband had not closed the flue from the night before's fire.

We keep it closed when not in use.

Please ask your husband his reason and post--I'm dying to know!!! :)

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M.B.

answers from Austin on

Closed...

Warm air rises... and rises right out of the chimney, leaving you cold!

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T.W.

answers from Denver on

You are absolutely right, it should be closed. It is very true that the heat and your money just flies up the chimney. I wouldn't even be as worried about the money as much as being flippin' cold! We are in an old house too and if the flue is open you can tell by the draft it creates. Close the flue.

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B.C.

answers from Norfolk on

Close the flue when not in use.
Does your husband like leaving a window open all winter/summer when heat/air conditioning is on?
Leaving the flue open amounts to the same thing.
Additional:
I don't think storm windows, double hung or otherwise enters into it.
A hole in the wall or roof, whether caused by an open window or an open flue is still a hole in the wall/roof.
In effect, by keeping it open you are PAYING to heat/cool the great outdoors.
As I see it, you've got 2 choices.
Either seal up the fireplace and never use it (they have magnetic covers which will work nicely) OR climb in there (clean out fireplace first, but it will still be quite sooty) and figure out how to open/close the flue yourself. It might be an ornery old beast, but you should be able to open/close the flue. If it is stuck and can't be moved - the landlord needs to come to fix it.

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B.K.

answers from Chicago on

My HVAC handyman says absolutely keep it closed. Leaving it open is like having an open window in your house... only one that is on the roof and sucks the heat right out. Closing it in the winter will save you way more than just pennies!

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C.P.

answers from Columbia on

Always close it. Fireplaces are known to waste tons of heat.

Your best bet, really, is to get a woodstove insert. That way, when it's not in use, it's fully sealed...and when it is in use, it's FAR more efficient at keeping the heat in your house instead of sending it up the chimney. Plus, if the power ever goes out, you can warm food on it, boil water, and keep the house significantly warmer.

Best of luck!

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C.B.

answers from San Francisco on

We close ours because not only does the heat go up, but the cold from outside comes down the flue. We find our heater kicks on more when the flue is open.

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S.F.

answers from Utica on

Definitely closed when not in use - you can actually feel the air flow being sucked out of the house when you sit by the fire place with the flue open
Its not saving you pennies its saving you much more than that - it causes an automatic draft when its left open
I suggest you just smile and agree with him and when hes out of the room just close it =)

1 mom found this helpful

S.L.

answers from Kansas City on

Close it. Also there have been cases, like we experienced, when no fire in the fireplace of having a bird fly in. We also had wasps come in. Heat rises, like you said, and you can even feel the cold come in if you leave it open and it's cold outside. Have him sit by the fireplace when it's cold and let him feel it.

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B.E.

answers from New York on

I used to leave mine open all the time and then I read on my oil company's website that it should be closed when the fireplace is not in use to prevent major heat loss. Also, if you don't clean the ashes up right away, you can have an issue with a puffback if the flue is open on a very windy day.

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M.R.

answers from Phoenix on

Only in the winter, CLOSED when not in use....otherwise I leave it open.

G.T.

answers from Redding on

I think closed when not in use, but during winter if we burned fires fairly frequently I always left it open just in case I forgot to open it when I started a fire...... been there done that, not fun.
If you arent feeling a breeze while standing in front of it, I wouldnt worry about the heat escape much. If you do feel a breeze, close it. I'm sure you can figure out how to work the flue, it's usually a handle right there near the mouth of the fireplace.

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M.H.

answers from Washington DC on

not only do we keep it closed when not in use but we cut a piece of insulation to fit in the space too. Its the hard foam kind so its easy to insert and pull out. We also have an old house with the original windows but we do have the storm windows too. Honestly, I'm not sure how much they help cut down drafts.

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R.M.

answers from Cumberland on

It should be closed-it saves more than pennies-warm air is no match for much heavier colder air-it's not so much that the heat escapes-it's that the frigid air pours in.

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A.C.

answers from Boston on

After my father left my mother learned real quick how to close the flue after a bat got in the house and gave the cats a run for their money. It should be closed and if you can't figure it out call a chimney sweep and have him/her show you what to do. Good luck.

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M.L.

answers from Colorado Springs on

Our flue is closed when there's no fire (and my husband is good at waiting until the fire is *completely* gone so there are no unneeded fumes in the house.)

We've had birds drop in - literally - which the cats have found very entertaining. It's not easy to get a frightened bird out of your house! Wasps and bees also like to use it as a secret entrance. If I could, I'd write "no vacancy" on top of the damper.

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H.G.

answers from New York on

Absolutely CLOSE the flue when there isn't a fire going. Heat does go right up. Also a great way for critters to get in. If you don't have a good chimney cap, get one because you will get something crawling, flying or falling in eventually. An HVAC guy should know that heat rises.

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