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Posted

Does this brick chimney (with issues of its own) location in relation to the furnace vent represent "a vertical wall or similar obstruction" as in G2427.6.3 #2 of the 2006 IRC and should be terminated two feet above the chimney? I told my clients that it was short but I wasn't sure how much. Thanks for any replies. Ed

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Posted

Hi,

Well, without looking it up, I believe the requirement is two feet above any vertical sidewall within 8 ft., but I'm not so certain that a chimney that's only about 2ft. on a side will make that much difference, but it will cost very little to add another 3-4ft. to that vent and install some guy wires. That's what I'd write.

OT - OF!!!

M.

Posted
Originally posted by mridgeelk

Does this brick chimney (with issues of its own) location in relation to the furnace vent represent "a vertical wall or similar obstruction" as in G2427.6.3 #2 of the 2006 IRC and should be terminated two feet above the chimney?

You betcha.

- Jim Katen, Oregon

  • 5 weeks later...
Posted
Originally posted by mridgeelk

Does this brick chimney (with issues of its own) location in relation to the furnace vent represent "a vertical wall or similar obstruction" as in G2427.6.3 #2 of the 2006 IRC and should be terminated two feet above the chimney? I told my clients that it was short but I wasn't sure how much. Thanks for any replies. Ed

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Definitely an issue. Violates the 10-2-3 rule.

Posted
Definitely an issue. Violates the 10-2-3 rule.

Based on memory the requirement for a chimney is the 10-2-3 rule. For a B vent, there is no 10-2-3 rule. The requirement is based on the slope of the roof (min. 12"). The 2' above the roof line within 10' applies when there is a sidewall within 8' horizontal feet of a sidewall.

I am still not fully convinced that the B vent needs to be extended.....

I am curious as to why there is a requirement to go 2' above any point within 8' horizontally of a sidewall, when there is only a 12" requirement elsewhhere. The only thing I can think of is that there would be a chance of venting back through an eave vent or window??

Anyone have an idea or answer?

Posted
Originally posted by Brandon Whitmore

. . . I am curious as to why there is a requirement to go 2' above any point within 8' horizontally of a sidewall, when there is only a 12" requirement elsewhhere. The only thing I can think of is that there would be a chance of venting back through an eave vent or window??

Anyone have an idea or answer?

I believe that it's related to turbulence. When the wind blows against a wall, it creates turbulence that can interfere with the drafting of a B-vent.

I suspect that the same thing would happen with the chimney in the OP.

- Jim Katen, Oregon

Posted
Originally posted by Brandon Whitmore

Definitely an issue. Violates the 10-2-3 rule.

Based on memory the requirement for a chimney is the 10-2-3 rule. For a B vent, there is no 10-2-3 rule. The requirement is based on the slope of the roof (min. 12"). The 2' above the roof line within 10' applies when there is a sidewall within 8' horizontal feet of a sidewall.

I am still not fully convinced that the B vent needs to be extended.....

I am curious as to why there is a requirement to go 2' above any point within 8' horizontally of a sidewall, when there is only a 12" requirement elsewhhere. The only thing I can think of is that there would be a chance of venting back through an eave vent or window??

Anyone have an idea or answer?

Is the chimney 2' taller than anything within 10' of it? Doesn't look like there is a 24" difference b/w that and the metal vent next to it.

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