Chimney: Is B-vent on top of masonry chimney possible?

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Old 04-18-12, 06:16 PM
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Chimney: Is B-vent on top of masonry chimney possible?

Is it possible to just add a metal "B-vent" chimney directly on top of an existing masonry chimney -- without the masonry chimney below being changed or any metal liner being placed in the masonry chimney?

The reason that I am asking is that one of the many chimney companies and masons that I had look at my chimney submitted an estimate that included tearing the existing chimney down to the roof line, then just adding a triple wall stainless steel B-vent on top of the existing chimney from the roof line up. According to them, the B-vent would go directly on top of the existing 8"x8" clay flue with an adapter, and no new liner would be placed in the existing chimney. This, of course, would be assuming that the existing chimney and clay flue from the roof line down is all in good condition.

Since they gave their estimate, I have been doing tons of research and I cannot find anything -- no codes, no descriptions, etc. -- that would address this particular situation.

Yes, it would make sense to at least add a liner to the existing chimney if possible, but an issue has come up regarding that. The issue is that going into the chimney is an existing 7-inch metal flue from the gas-fired steam radiator heating unit and a 3-inch metal flue from the gas-fired hot water heater. Apparently, since a 7-inch metal flue is already going into the 8"x8" clay chimney flue, the minimum new metal chimney liner size would have to be at least 7 inches. But, a 7-inch liner will not fit into an 8"x8" clay flue. So, a new metal liner or B-vent cannot be placed inside the existing masonry chimney without removing the existing 8"x8" clay flue all the way down.

So, again, my question is, "Is it possible to just add a metal "B-vent"
chimney directly on top of an existing masonry chimney -- without the
masonry chimney below being changed or any metal liner being placed in the
masonry chimney?"

P.S. This is a side-by-side twin home, so this is actually two chimneys instead
of one -- one for each house. The height of the chimney is about 10 feet up
from the roof line.

Here are two photos:

www.************/r/t8rtac/5

www.************/r/9unmvb/5
 
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Old 04-18-12, 06:25 PM
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Sorry, I may not have posted the links to the two photos in the correct format for them to work.

The two photos of the chimney are located a "tinypic-DOT-com", with the /r/t8rtac/5 and the /r/9unmvb/5 attached to the end of the link to see the two photos.
 
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Old 04-18-12, 06:32 PM
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Cant see the pics. Post pics to a place like photobucket.com and post the link to those pics back here.

8x8 ? A 7" liner should fit no problem.

Why are they taking the top of the chimney down?

If for whatever reason, rebuild it back with whats there. They still make clay liners.

Possibly time to find another contractor.

I will check the codes. You have to go to the NFPA,com to find that code I believe.



Mike NJ
 
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Old 04-19-12, 08:43 AM
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Chimney: Is B-vent on top of masonry chimney possible?

I'll try again with the phot links. The links are to ************ which is like photobucket.com.

Here are the two photos:

http://************/r/t8rtac/5
http://************/r/9unmvb/5

And, here is a link to the 2006 International Residential Code for New Jersey:

http://www2.iccsafe.org/states/newjersey/NJ_Residential/PDFs/NJ_Res_Chapter24.pdf

The chimney has to be taken down from the roofline up because the existing chimney is in bad shape and apparently cannot be repaired.
 
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Old 04-19-12, 08:49 AM
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Sorry, there must be something where I am not allowed to post links to the tinypic-DOT-com website here. That's where my two photos are posted. Every time I try to post the links, they get converted to all asterisks (****'s). I'll try again by clicking on the "Link" icon above.

http://************/r/t8rtac/5

http://************/r/9unmvb/5
 
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Old 04-19-12, 08:55 AM
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Sorry again. It didn't work. If your replace the asterisks in each link with "************", that takes you to the photos.
 
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Old 04-19-12, 09:04 AM
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Sorry again. It still didn't work. If your replace the asterisks in each link with "tinypic-DOT-com" that takes you to the photos.

I give up.
 
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Old 04-19-12, 09:16 AM
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Old 05-17-12, 02:42 PM
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it makes a difference on what your hooking to the flue.....for example if it is a wood appliance than B-vent would be a no-no...class A would be required.
 
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