Cutting class A pipe

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Ehouse

Minister of Fire
Jul 22, 2011
893
Upstate NY
I have a spare piece of 6" class A double wall insulated pipe 36" long. I need to extend my chimney (same pipe) 15"downward to rest in my support box. Can I cut the female end off the spare, or must I buy a 12" section plus a sliding adapter to the tune of 200 + dollars. I realize I will have to adapt the flue extender, and the warranty will be void but the chimney was here when I bought the house so it's probably not available anyway. I suppose I could sell the spares (have 3) to pay for the new pieces but I'd rather keep the loot. What do you think?

EHouse
 
Don't cut it. Sell it and buy the correct size. I can get class a at Menards for a lot less than $200. I think even less than $100.
Doug
 
This is Security Chimney International pipe and I haven't found any place to get it cheap. Why not cut it? Would it create a safety problem?
 
Ehouse said:
This is Security Chimney International pipe and I haven't found any place to get it cheap. Why not cut it? Would it create a safety problem?

Cutting it is NOT the way to do it. This is a manufactured UL approved piece.
It is also a safety issue.
Why dont you add it to the top/last section on the roof and drop the chimney down to rest in your support box. If its a straight run.
 
No cutting! Trade it for a 24 or 18" length or just let the chimney be taller. Is that an issue?
 
Thanx for your replies. Not trying to be obstinate but everyone is saying "don't!" but no one is saying why. North of 60, what would be the safety concern? The bottom of the pipe would be tight to the support box and the flue extension would protect the pipe insulation just as in a regular install.

Ehouse
 
If you cut it and your house burns down your insurance will not cover it as it is no longer a u.l. listed system. If there is a fire the inspector will have the manufacture send a rep to investigate, he will see the cut piece and automatically becomes your fault. Being in NY you could be held criminally liable should anyone get hurt
 
Ehouse said:
Thanx for your replies. Not trying to be obstinate but everyone is saying "don't!" but no one is saying why. North of 60, what would be the safety concern? The bottom of the pipe would be tight to the support box and the flue extension would protect the pipe insulation just as in a regular install.

Ehouse

A metal chimney is a integrated system. You can't mix and match or alter the components without violating the UL certification of the system. The pipe doesn't just sit in the support box, it sits in a socket mating with the male connection of the support box by a twist-lock fit. Don't cut the pipe.
 
As BeGreen says...........You can use coffee tins, cut the bottoms out, join them all together and insulate it with fiberglass and still make it work. Is this right? No! It clearly states about modifying a UL approved product and putting it in use that it has not been tested for under these conditions. Your attachment points will become breached which is unsafe. Gone Fishin. Gotta scrape the ice off of my boat windows 1st. :)
 
One more time......The pipe has a UL approval. It was tested and found safe for the intended application as it is. If you cut it, it is no longer what UL tested and it probably is no longer safe for the intended application, because it will not perform the same, may fail to protect combustibles at the UL specified clearances. In other words, in may burn your house down.
 
The pipe doesn't just sit there. It is held captive. Even if it sort of worked, it would not seal the connection and the pipe would not be locked in place. With the first big puffback or windstorm you would totally regret doing this. You'd be lucky if all you had to do was replace your underwear.
 
I have no arguments with the above comments. thanx for the replies. However, BeGreen, there is no twist lock male receiver in the ceiling support box nor is there one listed for the securities chimney international ASTH+ product line. It appears that the female end of the last pipe simply rests in the box.

Ehouse
 
It's your house and you can do anything you want, including burn it down or asphyxiate the occupants. Though you might want to look at page 5 of Security's installation guide for SecureTemp ASHT+ pipe first.
 

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BeGreen,

Thanks for your diligence on my behalf. Be assured I will not cut the pipe. There is no male connector in the ceiling support which I removed from my install. This may be another feature of a truly crappy "professional" installation. The only support for the entire 38' of chimney was this support box in the basement, the firestops didn't cover the openings in the floor framing (6" spaces either side) and the pipe rested against framing in 2 places. All of these issues are being corrected according to specs. Forgive my persistence as it has led to the discovery of this connector problem with the support piece. This install was done over 5 years ago before I bought the house. I will call Security International Monday about the missing anchor piece and post.

Ehouse
 
It's possible that they installed another brand support box. Good to hear that you are tearing it out and putting it back together correctly and redoing the firestops. 38' is a really tall flue. That thing must draft like a vacuum cleaner. Do you have a key damper on the stove to slow it down?
 
I removed the section from the first floor ceiling to the basement, so the chimney height will be about 10' less. The little Weso stove has a primary and secondary damper. The gentleman at the Weso parts place in NH was adamant about not placing an inline damper in the stove pipe. We'll see how it works.

Ehouse
 
Very glad to hear this is being done correctly. I hope to hear back from you to see how you made out and how it's working.

pen
 
As an update, I spoke to Securitiy Chimneys International this morning. Tech.
support says the screw into the support requirement was implemented in the last year or so and that it is ok to use the base support without the male coupler with the pipe end merely resting in place. Go figure. Don't worry, I still won't cut the pipe! Thanx for your help.

Ehouse
 
I have to ask, if one uses the old base is there a direct and solid seal between the connector and the class A pipe? What holds the class A captive and stops it from rotating?
 
There is a flue extender that is fastened with cap screws ( self tapping) to the circular end piece that bridges the inner and outer liners. This mates with the inner liner and protrudes from the support box. Presumably, the connector pipe is fastened to this, also with screws and so on to the stove connection thereby preventing rotation of the pipe. Also it is stated somewhere in the product lit. that you can (not must) put a couple screws in any pipe joints to prevent rotation. I noticed that at least one hardware store is selling other brand's support boxes with no base locks. Perhaps the industry is waiting for the inventory to run out before condemning these installations? What does Selkirk or Simpson show as currant installation procedure as opposed to, say 2 years ago.

Ehouse
 
Duravent has been this way for at least 5 years. I thought our previous (quite old) Selkirk installation locked in, but it has been a long time since I pulled it and I can't remember.
 
It was one of those two at an Ace Hardware, can't remember which. Examined my $100.00 12" piece of pipe that I bought today and they don't seem to care much about sealing the female end. Insulation was protruding all around the inner liner. In fact I remember now that they don't seal the female end to allow for expansion if the inner pipe.

Ehouse
 
BeGreen said:
Duravent has been this way for at least 5 years. I thought our previous (quite old) Selkirk installation locked in, but it has been a long time since I pulled it and I can't remember.
BG, My Selkirk Super Pro Chimney, first section, screws to the stove pipe adapter, and then that just sits in the ceiling support box. Page 5 of the install manual, http://www.selkirkcorp.com/WorkArea/showcontent.aspx?id=1632 It was just installed this year in February.
 
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