How to cap off unused chimney flue

[shoottmx]

We have a fireplace in our family room that we never use--I know--one of my hobbies is creating high cost firewood but I give that to another high cost firewood producer to burn in his wood stove.

To the issue. During certain temp/humidity conditions we get a downdraft that stinks like a used chimney, sometimes it's really miserable. We also get the smell when the house is closed up and we run the clothes dryer. Can we just cap off the top of the flue? The chimney was cleaned after we last used the fireplace .

Thanks guys,

g

[Pirate]

Cap top or bottom. Just be sure the fireplace is the only thing that uses the flue!
Family room. Fireplace. Blocking flue. Just doesn't sound right to me!

I'm now living in FL and miss having a working fireplace.

[vernonator]

cut a piece of 2" foam insulation to fit the flue at the bottom, wedge it up there and use spray foam to seal the edges. Air tight and insulated and not permanent.

[shoottmx]

vernonator said:

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cut a piece of 2" foam insulation to fit the flue at the bottom, wedge it up there and use spray foam to seal the edges. Air tight and insulated and not permanent.

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This is looks like the best option for me!! Thanks vernonator and everyone else who replied.

g

[arthropod98]

shoottmx said:

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[blockquote]vernonator said:

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cut a piece of 2" foam insulation to fit the flue at the bottom, wedge it up there and use spray foam to seal the edges. Air tight and insulated and not permanent.

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This is looks like the best option for me!! Thanks vernonator and everyone else who replied.

g

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[/blockquote]

i think i'd still wanna seal at the top . . . JMHO. i'm just picturing water building up or something getting down in there.

[Snipe Hunter]

I sure wouldn't put spray foam in a flue. It's probably a good way to start a chimney fire for the next owner. It will be a bugger to get out if you ever have to sell the house.

I'd probably cap the top with aluminum foil and put a rain cap over it to hold it in place. I certainly wouldn't stick something flammable in it.

[EatenByLimestone]

There are dampers that can be installed at the top which will keep rain out, yet are openable should you want to use the flue.

[EricU]

Snipe Hunter said:

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I sure wouldn't put spray foam in a flue. It's probably a good way to start a chimney fire for the next owner. It will be a bugger to get out if you ever have to sell the house.

I'd probably cap the top with aluminum foil and put a rain cap over it to hold it in place. I certainly wouldn't stick something flammable in it.

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good point about messing up the flue. I made some sheet metal caps for mine, and they blew off. Really frustrating. I think that means there is a pretty big force from underneath helping to lift them. So you should probably add something at the bottom that is easy to remove.

[EatenByLimestone]

Draft is the force and it runs off the difference in temperature between inside and outside. There are balloons you can buy that fit. In the chimneys too.

[ridgeline]

I closed my chimney off with a stainless cap that included a damper similar to this combo cap damper

This stops the drafts but is not permanent should you change your mind or plan to sell your house at some point.