Stuff for rigid liner

[precaud]

This weekend I should be finishing the masonry portion of my fireplace transformation, and moving on to the liner components. Since I have a straight shot down the chimney now, I'm going to go with a rigid liner. Some questions:

A search on this site came up with Elmers of Maine as one source for rigid. That's an awful long way to ship this stuff (I'm in NM)... are there any other sources for it?

I'm thinking of extending the liner a couple feet past the chimney top. If I go that route, I know it's not wise to expose single-wall pipe to the cold, so I was thinking of 4 feet of double-wall insulated, half in the chimney, and then singlewall the rest of the way down. Make sense?

In a setup like this, the chimney top plate seems to bear the weight load. Is that correct, and acceptable?

From the tee to the stove, is there significant draft benefit to using two 45 degree angles versus two 90's? If so, who makes a tee with a 45 degree outlet? I've never seen one.

Thanks for your thoughts.

 

[saichele]

Lots of vendors for rigid liner - some advertise onthis site (along the bottom usually).

I think there are restrictions on how far above the chimney you can extend liner, like only a few inches. Otherwise you need one of the flue extensions.

Most manufacturers will tell yu how long a length you can have supported just by the top plate, but I think 2 stories is usually about it.

I don;t think they make 45deg. T's (would they be V's or Y?), but intheory a long, large radius curve would be better than a T, a 90 better than a T, and 2 45s better than one 90.

Steve

 

[begreen]

Wish you were closer. I have about 20 feet of 8" stainless.

 

[precaud]

Wish you were closer. I have about 20 feet of 8" stainless.

Sigh. I'm curious; did you choose 8" for the 3CB, or was it already there?

 

[MountainStoveGuy]

In the stove venting world, we treat 2 45's like they were one 90* for calculating restriction. In the real world i would agree with steve and say that there is less restriction going through 2 45's then one 90*. I think a more gental bend is benificial for exaust gas flow.

 

[njtomatoguy]

MSG-

I second that vote for Steve- In the plumbing world, it flows downhill, and we never use a 90 where we don't have to-- smooth, continous flow-- 2 45's are better than a 90 going downhill, also use 2 45's in venting , which is technically "uphill"


ELK?

 

[begreen]

Wish you were closer. I have about 20 feet of 8" stainless.

Sigh. I'm curious; did you choose 8" for the 3CB, or was it already there?

No, this was in our main chimney. It was connected to an old Majestic insert for a year, then we switched to a pellet insert in that location. Now chimney is gone and pipe is still here.

 

[elkimmeg]

njtomatoguy

In the plumbing world, stuff flows downhill

Years back when I did a lot of septic and swewer lines , we used sweeps for change in directions. They were far superior and
more clog resistant then elbows or 90's I never see them amymore. I wonder what happened to them? The same principle could and should be applied to venting

 

[precaud]

Using two 45's instead of one 90 makes alot of sense flow-wise, and I think I may have enough room to use them.

Now, let me steer the discussion to something perhaps more controversial, using 22 ga. steel pipe vs 24 ga. stainless for the liner. I've been heating with wood since the mid-70's and I have never seen even a 24 ga. steel pipe get eaten through from the inside. Maybe the low-humidity conditions here in NM are a factor in that, I don't know. But this experience makes me question the need to spend three times as much for stainless pipe vs a heavy grade of steel (except for the topmost pipe and the hardware that's exposed to the elements.) And using steel would allow me to use my current set of brushes. Whadya think?

 

[precaud]

Well noone has responded... so I guess a rigid liner of 22 ga. steel is as good or better than 24 ga. stainless...

 

[Dave_1]

precaud,

fwiw,

You might want to scroll down the left side of the following link to:
`Need help? Have a question?'
http://www.hartshearth.com/chimney/chimney_images.htm
and ask your question before constructing that chimney.
After you get an answer then check it out on a few more chimney installers/sellers for their views.
Have a good one.

Dave

 

[precaud]

Thanks Dave. The chimney is already built; the question is only about the liner...

 

[elkimmeg]

Are you asking the difference between 22 gage connector pipe to 24 gage stainless steel liner pipe?
Conector pipe is just that it is not rated to be used as a liner. However a higher rated pipe stainless steel can be used as a connector pipe. I don't get your question. Are you looking for affirmation to violate code by using incorrect connector pipe as a liner? Maybe that's why no one responded or we were consused and do not understand what you are asking. Are you asking the difference between stainless steel 22 gage vs stainless steel 24 gage liner pipe? Both are acceptable if rated to HT2100 or ul standards

 

[precaud]

It's not a question about Class-A chimney, or code, or labels; it's about the materials - 22 ga. steel pipe vs 24 ga. stainless. You might say I'm questioning the code, since nothing in my experience supports the need for what it calls for in this case. I thought I set up the context for my question pretty well, but let's try again.

Given that, in 30 years of woodburning, I've never seen even a 24 ga. steel pipe corrode from the inside,
Given that, perhaps the low-humidity conditions here in NM are a factor,
Given that, stainless pipe costs 3X as much as steel,
The question is: As a rigid liner in a masonry chimney, why is 24 ga. stainless superior to using 22 ga. steel pipe?

 

[saichele]

It's not a question about Class-A chimney, or code, or labels; it's about the materials - 22 ga. steel pipe vs 24 ga. stainless. You might say I'm questioning the code, since nothing in my experience supports the need for what it calls for in this case. I thought I set up the context for my question pretty well, but let's try again.

Given that, in 30 years of woodburning, I've never seen even a 24 ga. steel pipe corrode from the inside,
Given that, perhaps the low-humidity conditions here in NM are a factor,
Given that, stainless pipe costs 3X as much as steel,
The question is: As a rigid liner in a masonry chimney, why is 24 ga. stainless superior to using 22 ga. steel pipe?

You might have heard that there's a right way, a wrong way, and an Army way? It's like that.

All your comments indicate that ordinary steel pipe woiuld be fine, and for years and years it was. And it would probably be fine. Esp. inside an existing chimney (you could, in theory do without a metal liner entirely if you have an existing chimney) But NFPA and the Gods who hand down codes say it's not. So it doesn't particualrly matter what you think or what would work.

Why, you might legitimately ask? Because your homeowners insurance will likely want to see a permit and inspection. Otherwise, onthe off chance something does go wrong, they'll squirm out of paying off your house. So you're stuck with no house and whatever debt is outstanding on your mortgage. So the 3x extra you pay for the liner is like the 500 you pay to have airbags - a mandatory expense for something you'll probably never use. But inthe 1 in a million case, it might help.

That said, if you own the house outright and don't mind losing it, then it's your call. Or if you know the permit guy well, maybe that's an avenue. But for most they just have to suck it up and pay the extra cash, $500 to maintain protection on the $200,000 locked up int he house.

Steve

 

[elkimmeg]

Steve is right but the real reason is the ability to withstand 1800 degree chimney fire common 22/ 24 gage mild steel can not .Stanless steel tested and certified can. Common midl steel will de- form warp and fall apart at 1800 degrees it is not tested an unlisted for liner applications, for the previous stated reasons. IT's using the correct material for the application. People do get lucky streeching the limit but it is unfair for those that know, to suggest it is ok to do so. We all understand the money difference.

How safe would you feel if I put inferior brake pads on your car? They may stop the car in normal situations, but when you really need them, they can fail. One of the main reason one lines an existing chimney, with an approved ss liner, is the added protection should things go wrong. Code also defines the liner to be crosive resistant. mild steel is not. Maybe in your climate being dryer it is less of an issue/ Sulfer and moister are part of the wood burning process, each exit up that chimney. Combined is an acid H2/S04 which eats mild steel.

 

[precaud]

OK guys, thanks for your input. Unfortunately, work requires my full attention right now, so I'll follow up later.

 

[precaud]

Well I agree, Steve, this is the "army way" equivalent. Code overrides and obviates the need for common sense, and allows the appliance to be misused in safety.
Inspection? Not in NM... never heard of it.
Chimney fire? The flue gets cleaned every year, whether is needs it or not. I'm always present when the stove is burning. And, as stated elsewhere, I tend to burn hot, so the flue stays pretty clean - no long, smouldering burns. And no overnight burns, either.
Elk, the analogy to inferior brake pads... I'm not talking about installing an inferior part. As I've said, I question whether I need the "added protection" that stainless offers. I've never seen corrosion. I have 19-year-old 24 ga. 5" pipe that I've used on my old Jotul that is as good as new.
So, my point is - intelligent and consciencious use is THE most important safety factor.