*Bob H - clearance question

**Marc M** · 07-28-2011, 09:56 PM

Bob, is there a clearance that you know of with fuel pipe and factory built fireplace vent? I'm aware of the potential transfer of heat via pipe/wood.

Similar Threads:

Bo Tasso · 07-29-2011, 05:11 AM

I hope that Bob can answer your question.

My concern is there is no attic radiation shield installed to keep insulation from being placed or blown in and coming in contact with the chimney.

The chimneys I deal with all require them. Obviously it is a problem with the gas pipe in the way.

I also question the clearance between the chimney pipe & the rafter. Does that meet the manufacturer's requirements?

**Marc M** · 07-29-2011, 07:49 AM

Hey bob,
You're correct with the clearance to comb and no insulation sheild.... There's also other issues with this installation not shown in the image. I was just curious about the gas line. I've seen this a few times but never asked. This was the only image of this contact that I was able to find to use as an example. Just an arbitrary question.

James Duffin · 07-29-2011, 08:21 AM

I even hesitate to ask with the fear of being jumped upon....but is that triple wall pipe?

**Marc M** · 07-29-2011, 08:29 AM

Originally Posted by James Duffin

I even hesitate to ask with the fear of being jumped upon....but is that triple wall pipe?

I dont really know, sorry. I dont suspect it is. If I can remember, this house was a 2004 and the box was superior if that helps. I didnt go on the roof to verify via termination. Plus, the inspection was a while ago.

James Duffin · 07-29-2011, 10:37 AM

I think the Superior wood burners use a Security System FTF series chimney that requires a 2" clearance and follows the same codes as a masonry chimney.

**Bob Harper** · 07-29-2011, 11:54 AM

Several issues here:

As Bo pointed out, you need an attic insulation shield on top of that firestop.

You do not appear to have clearance to combustibles but again, we are not furnished with make and model to verify clearances.

If this is a woodburner, then it is a "chimney" and not a "vent".

As for the gas pipe, there is nothing specific I can find in the code preventing a sch 40 steel pipe from being in proximity to a listed chimney per se. When you read the IFGC commentary, you will see their concerns are where piping is located in places that are corrosive or can be damaged. Steel piping is allowed to penetrate masonry and factory built fireplaces for gas appliances so its presence near heat is not a problem in and of itself. If this was CSST, I would be concerned about the heat against the plastic protective coating.

The pipe as shown appears to violate clearances, which are air spaces. In this case, it would reduce cooling and actually tend to conduct heat to the nearby framing.

BTW, that gas branch going down the stud cavity would need strike protection at the top plate.

Now, as for James and his comments, I'm not sure where he's coming from. He made a wise crack about me in another thread accusing me of being a SA, which I took to mean smart a$$. I wish I knew what I did to offend you but none was intended by me. However, when I asked you to support your contention that triple walled pipe was zero clearance, you failed. Now, once again, you bring up triple walled pipe with no clear position on its relevance here. Do us a favor James and for the love of God please tell us what magic importance you think triple walled chimney holds and name what manufacturers & models of triple walled chimney you have found that are rated for a zero clearance. If you cannot product this information then please quit tossing it into discussions as it only clouds the issues.

Thank you.

**Jerry Peck** · 07-29-2011, 02:50 PM

Is that a flexible pipe section/elbow in there? Doesn't look right to me.

**Jim Hintz** · 07-29-2011, 03:38 PM

Originally Posted by Bob Harper

Several issues here:

As Bo pointed out, you need an attic insulation shield on top of that firestop.

You do not appear to have clearance to combustibles but again, we are not furnished with make and model to verify clearances.

If this is a woodburner, then it is a "chimney" and not a "vent".

As for the gas pipe, there is nothing specific I can find in the code preventing a sch 40 steel pipe from being in proximity to a listed chimney per se. When you read the IFGC commentary, you will see their concerns are where piping is located in places that are corrosive or can be damaged. Steel piping is allowed to penetrate masonry and factory built fireplaces for gas appliances so its presence near heat is not a problem in and of itself. If this was CSST, I would be concerned about the heat against the plastic protective coating.

The pipe as shown appears to violate clearances, which are air spaces. In this case, it would reduce cooling and actually tend to conduct heat to the nearby framing.

BTW, that gas branch going down the stud cavity would need strike protection at the top plate.

Now, as for James and his comments, I'm not sure where he's coming from. He made a wise crack about me in another thread accusing me of being a SA, which I took to mean smart a$$. I wish I knew what I did to offend you but none was intended by me. However, when I asked you to support your contention that triple walled pipe was zero clearance, you failed. Now, once again, you bring up triple walled pipe with no clear position on its relevance here. Do us a favor James and for the love of God please tell us what magic importance you think triple walled chimney holds and name what manufacturers & models of triple walled chimney you have found that are rated for a zero clearance. If you cannot product this information then please quit tossing it into discussions as it only clouds the issues.

Thank you.

Hey Bob, found this link about triple walled chimney pipes and "almost" zero clearance installation. The theory of the outer surface remaining cool sounds correct, kinda like the theory behind Penguin Triple Pane Windows. Best Wishes - Jim. How Safe Are Triple Wall Chimmeys? | eHow.com

**Bob Harper** · 07-29-2011, 07:03 PM

Jim, sorry but that link is a useless fluff piece. First of all, the UL 103HT listing is for 2,100F--not 1,000F. Actually, it is 1,000F for 16hrs, 1,400 for 1 hr then 2,100 for ten min tested x 3. Triple walled thermosyphon chimney was invented by Robert K. Thulman in 1949---not *latest in current technology*.

Note how they referred to it as "nearly" zero clearance", which is part of the problem. So many people keep hearing that damn "zero clearance" term that many people incorrectly ASSume that all factory built fireplaces, chimneys and vents are rated at zero clearance. This has lead to a lot of unfriendly fires and people hurt. Can we stop this insanity at least on this forum? Pleeeeeease?

Unless somebody can provide a link to several models of triple walled chimney that are listed to UL 103HT at a zero clearance to combustibles, please leave a sleeping dog lie.