Chimney height

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Chimney height

Postby 67GTO » Tue Oct 18, 2016 2:35 pm

Hello everyone. I need advice badly.
To start, I have a brick house (which is around 1100 square feet) with a masonry chimney. The flue blocks are surrounded with cmu up to roof and then transitions to brick on the outside. The top of chimney is about 2'-4" above the ridge, but total height of chimney is around 9'-0" from where wood stove pipe pokes through wall into chimney to top. The flue is 5 3/4" x 6", and our stove is 6" dia.
I had a company come out and clean my chimney. The guy told me that there were cracks in the flue, and that there was portions that had glazed creosote on it. He said that the cracks were partly (if not mostly) to blame for the poor draft. I asked how big the cracks were and he told me that they weren't that big but you don't need much to cause a problem. He said he wouldn't even start a fire if it was his family. He told us it would be around $2400 to remove the flue and put an insert in.
Questions:
1. If the cracks aren't all the way through the cmu, how can it be causing a problem?
2. I've read where if the chimney is shorter than 12'-0" than there's inherently a draft problem, so if he replaces with the same height are we still going to have a blow back issue?
I know there are questions I still need to ask, I just don't know what they are.

Please help. I wasn't prepared for this and now it's mid Oct. My fault for letting the chimney cleaning slide down the large priority list.
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Re: Chimney height

Postby matt walker » Wed Oct 19, 2016 3:48 pm

What sort of stove are you running G? Can you get in there from the top with some fireplace mortar and a trowel on a stick or something and give the inside a good seal?

I would hate to recommend running it and you ending up with issues. On the other hand, what did we ever do before liners? Burned anyway. Still, old box stoves and crappy chimneys are unquestionably extremely dangerous, so.......yeah.

To be clear, there isn't much danger of lots of chimney gas leaking into the space. You live in a climate where draft is going to be good most of the time, and you'll know if it's not. It's that it raises the danger of chimney fire, lets air get to a potential chimney fire, and lets a potential chimney fire out of the chimney.

Hope that helps some.
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Re: Chimney height

Postby 67GTO » Wed Oct 19, 2016 4:21 pm

Thanks Matt,

It's an older New Englander with the catalytic thing removed (it was burned up).
The house is a Late 60's brick.

We've been having poor draft issues since we got the house.

Would the mortar stick to the glazed creosote? Do you think the height (or lack of) of the chimney is an issue?
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Re: Chimney height

Postby matt walker » Wed Oct 19, 2016 10:52 pm

I really don't know the answer to those questions G, every situation is unique. That old stove, with no cat, and a bad chimney, are not a great combo. I'd probably just start over, put in a new metal chimney DIY in a better location if one exists, and maybe even upgrade the stove. You'll still be into it a few grand, but you could put in a system you want where you want it, rather than just fixing a crappy setup.

That's my advice. Good luck G.
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Re: Chimney height

Postby 67GTO » Thu Oct 20, 2016 2:15 pm

Thanks again Matt
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Re: Chimney height

Postby thickstrings » Wed Nov 02, 2016 2:42 pm

" Life is art...Live a masterpiece"
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Re: Chimney height

Postby 67GTO » Wed Nov 02, 2016 4:24 pm

Thanks Thickstrings.
I'm stuck removing the clay liner because of the size. The liner is 5 3/4" x 6", and the stove is 6" dia.
I'm biting the bullet and removing it this weekend. Then I'm going to put in a steel one and extend (like you said) an additional 2 or 3 feet.
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