Problem with concrete chimney


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Old 02-08-11, 03:35 AM
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Problem with concrete chimney

I have a gas furnace which vents to a concrete chimney. Yesterday I heard a noise outside which I thought was ice falling from the roof. When I looked I found that an approx. 2' section of my chimney had fallen off. There is another secion which is cracked & is about to come down. I think that moisture got behind the concrete & froze, cracking the concrete. What is the best way to repair this? What concrete mix should I use? I live in upstate N.Y., so the cold weather is going to be an issue. I'm hoping that I can do a temporary repair which will hold up till spring. I'm not sure what this chimney is lined with. The material is black, which to me resemble cinders. Can anyone advise me on what's the best way to repair this? Thanx.
 
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Old 02-08-11, 05:46 AM
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First of all, you are going to have to figure out a different way to vent the chimney. Gas appliances should never vent to a masonry/clay liner chimney for the very reason yours has failed. You probably have significant damage to the structure of the chimney if you have vented this way for very long.

Gas combustion creates a damp exhaust that condensates on cold porous masonry. Combine that with the effects of freeze thaw and cold temps and you will get progressive damage. Use whats left of the chimney for a conduit for a smaller appproved metal exhaust system but only if the chimney structure is deemed safe.


bs5
 
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Old 02-08-11, 06:15 AM
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This could be ugly, the chimney may not be repairable

Can you post some pictures?

http://forum.doityourself.com/electr...your-post.html
 
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Old 02-08-11, 02:46 PM
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Originally Posted by bullshooter5
First of all, you are going to have to figure out a different way to vent the chimney. Gas appliances should never vent to a masonry/clay liner chimney for the very reason yours has failed. You probably have significant damage to the structure of the chimney if you have vented this way for very long.

Gas combustion creates a damp exhaust that condensates on cold porous masonry. Combine that with the effects of freeze thaw and cold temps and you will get progressive damage. Use whats left of the chimney for a conduit for a smaller appproved metal exhaust system but only if the chimney structure is deemed safe.


bs5
Great. I've owned the house for 7 yrs. & the chimney was this way when I bought the house. It's not even block, it's poured concrete. I'll try to get a pic up as soon as I figure it out.
 
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Old 02-08-11, 02:53 PM
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"It's not even block, it's poured concrete"

Interesting, I don't think I've ever seen a poured concrete chimney. Are you sure it isn't brick/block that's been stucco'd? Pics will be nice
 
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Old 02-08-11, 03:40 PM
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the temporary repair is to get some flexible stainless steel pipe for the bends & duct pipe for the straights,,, i'm w/everyone else - never saw a cast conc chimney,,, originally from binghamton, i worked all over nys, too - never saw 1.

if moisture got ' behind the concrete ', its not concrete but faced w/mortar,,, w/your level of expertise, i'd think hard prior to trying this work,,, using any conc mix in this weather requires special curing methods, reinforcement, & mix designs.
 
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Old 02-08-11, 07:01 PM
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Originally Posted by stadry1
the temporary repair is to get some flexible stainless steel pipe for the bends & duct pipe for the straights,,, i'm w/everyone else - never saw a cast conc chimney,,, originally from binghamton, i worked all over nys, too - never saw 1.

if moisture got ' behind the concrete ', its not concrete but faced w/mortar,,, w/your level of expertise, i'd think hard prior to trying this work,,, using any conc mix in this weather requires special curing methods, reinforcement, & mix designs.
I don't know what's behind the concrete. The substance is hard, & resembles crumbled coal. To be honest, I don't know what in hell the previous owner's did. By the looks of the chimney I think it was formed & poured around this substance. This winter has been brutal, & even if I get a contractor here, I don't know what they can do with it in these conditions. I've done some concrete work, but in this weather, I'm out of my league. My camera is on the fritz, so I'll try & figure out how to get a pic up. Thanx.
 
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Old 02-09-11, 02:46 AM
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Originally Posted by marksr
"It's not even block, it's poured concrete"

Interesting, I don't think I've ever seen a poured concrete chimney. Are you sure it isn't brick/block that's been stucco'd? Pics will be nice
Nope, no block. I'm positive it's poured as there's enough concrete missing that I can tell that there's no block.
 
 

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