To Rigid or Not to Rigid? That is the question.

[Benchwrench]

I have an outside wall chimney some 25' and is a straight shot down a 12x12 clay flue (minus the smoke shelf, of course)

I have on order a new 3 Cu. Ft. insert promoted up to a whopping 97k btu rating!
I want to make sure the new liner install will hold up to the years of future burns and I can sit back with my hot coco as I thank you guys for such a wonderful site.

I'd like to ask you guys a few questions regarding my new insert installation, I hope you don't mind, it's in regard to utilizing rigid pipe.

I was looking at a lot of posts regarding the pros and cons dealing with the installation of rigid lining for the above application.
I was looking a BrotherBarts' picture of his offset posted some time ago so I did some digging through the archives. I'm not sure if anyone or anything has changed their opinion or the rules since then.
From what I was able to glean, I've found double wall and triple wall rigid pipe.
First of all, is rigid what they consider "class A" pipe?
Since my chimney has no offsets, would you guys lean towards going with rigid instead of flex? if rigid, what would be favorably recommended? would I buy double wall or triple wall? do I also insulate rigid just as a flex liner since it's an outside chimney ?
Is there a connector needed at the bottom of the straight run of rigid to mate to either a 45 or 30 deg. offset that connects to the top of the insert?
Then there's all the connections every 4'... do I slather cement at each junction or what?
I really want to do the right thing for this rather large and high heat output insert . It is my understanding that rigid wall pipe is by far thicker than flexible liner so I'm guessing that it'll either last longer or take longer and hotter burn cycles.

The wealth of knowledge found here is very valuable. So thanks in advance for your feedback

I know I can use thinner flex the whole way down but...??? what about Rigid (I'm so confused )
Is rigid the right choice for this application? Did I supply enough info?

 

[Jags]

If you can make rigid work, I would stick with that. The smooth walls will make sweeping it easier in the long run. This is just my opinion.

 

[cmonSTART]

Ok, it sounds like you're installing an insert into a conventional fireplace with a 12x12 flue.

Some clarification: Class A pipe (double and triple wall) are very different from rigid chimney liner. Class A pipe is a stand alone chimney system for those who do not already have one.

The choice between rigid and flex liner: I install both, but more often flex. I think rigid is a better product and certainly performs better because of the smooth wall. Rigid tends to be a bit more expensive but for some of my customers the cost is about the same considering it can be easier to install in some circumstances. Whether you go with rigid or flex, be sure to insulate it with the appropriate product. It does make a difference!

*if you do choose rigid you will probably need to have a small section of flex on the bottom to navigate into the fireplace and connect to the stove.

 

[Hogwildz]

Insulated rigid double wall here, with 5' of flex through the smoke shelf. Love the rigid.

 

[Green Energy]

The double wall class A provides the insulation through the double wall. This would be overkill to use as a chimney liner, although you could if it will fit and you want to spend the extra money. If you go rigid (or flex), you will want to insulate the liner with the proper (rock wool) insulation to keep the heat in the flue pipe.

Me - I went with a 25' flex in an exterior chimney. Yes, the liner is not as thick and has a spiral walled as opposed to flat wall. With dry wood and a EPA stove, I get about ~ 4 oz of talcum powder-type ash when I do my annual cleaning. Cleans up pretty good. It was fairly easy to install myself.

 

[bpm44]

I recently relined the chimney for our Revere insert with Simpson 6" oval rigid duraliner that is factory insulated. The previous owner had a rather shoddy mix of un insulated 6" round flex and single wall pipe attached to a no-name deathtrap insert that is now in the junkyard. It was installed by a local "pro". My run is exactly 15'. It went together very easily - no cement needed, 4 ss pop rivets per section- and is suspended from the top of the chimney. If your roof isnt really steep and you have room to work up there i would recommend having an assistant to help with lowering the sections in during assembly. You would use a short piece of flex and appropriate adapter to get around the smoke shelf and connect to the stove, the duraliner catalog has all the necessary parts that will work together. I found that the northline express website had a link to the Simpson install directions and product catalog. Did a lot of research and planning before doing the install so that I knew what parts I needed and how they went together.

I've used other Simpson products in the past and have been very happy with them.

I've only had two fires since putting the new liner in so I can't say yet if it stays cleaner or performs better just yet, but I think it is going to work just fine, and I know I'll sleep a lot better knowing that I have an insulated liner in there that is done the right way.

 

[Benchwrench]

Could you guys clarify and name some of the products that would be used for this install application utilizing a rigid liner?
After what I read above from all your guys posts, I think what you're trying to say is single wall is what to look for, and I would be insulating it just as I would a flexible liner by using a foil backed ceramic blanket and SS sock. Is this correct?

My dilemma is this;
After looking at Simpsons' "duravent/liner" and looking at all their various catalogs, I find a need to narrow things down a bit to just what rigid liner would work regardless of who makes it. Since this is a insert going into a masonry chimney, I want the right rigid product but I don't know the names of the particular rigid liners out on the market that I would require an insulating wrap. So does this mean I should be looking for a Single wall product?
In regard to a double wall rigid liner; does this mean a person wouldn't have to buy the insulation kit, and that the double wall rigid liner is packed at the factory with insulation? would this also be a product to consider? like everybody else, I just want to get the correct product type.

Any suggestions as to the specific name or line of rigid would be greatly appreciated.
------------------------

To follow up...

Jaggs,
I feel the same way.


cmonSTART,
Love your moose. Thank you for your website, it has some great stories and beneficial info.
I also have to deal with another fireplace located in the basement. The chimney cap seems to pull smoke from the main FP sometimes so I have to either stagger caps or install some sort of blockage up top. Right now the basement FP is not in use.
Since you're in the know, could you please list a brand and type of rigid liner to use? I'd be grateful for that bit of info to get me started in the right direction.


Hogwildz,
(a little envious) as your set up is very similar to what I am proposing.


Green Energy,
You bring up a good point of DIY liner cleaning, I priced out a brush and extensions that total much less than it would be to hire out just one chimney cleaning.
Will see how things go from here, I've got a lot on my plate at the moment.


jeeper,
I bookmarked that website, they should change their name to " tons-o'-stuff " Thank you for that.
My roof is only a 7/12 pitch and the chimney is only about 2' high near the peak.
If I do this myself I'd need to come up with some sort of contraption to hold the pipe below while the newer section is being rivited. I'll have to do some digging for info for that as well.
After all this installation is over with, I too will sleep better. jeeper, and all you other guru's, thank you .

 

[bpm44]

Yes, you are correct in that the double wall rigid liner is pre insulated and no other insulation needs to be added.

The product I used is Simpson Duraliner. It is a high temperature, factory insulated double-wall masonry relining system, and comes in 6" and 8", and round or oval.

I used oval because I re lined an 8 by 12 terra-cotta flue that had inside dimensions of 6 3/4 by 10 1/2. Round would not fit.

I would used:

(3) 6" by 48" sections - p/n 5 sp-4648-op
(1) 6" by 36" section - p/n 5 sp-4636- op
(1) 6" oval extend-a-cap. p/n 5 sp-4687-o

You may need additional parts as your install sounds slightly different than mine.
Probably a:
Oval to round 36" flex p/n 5 sp-4636-OR. This will get you past the smoke shelf.
And a:
6" duraliner 30degree stove connector p/n 5 sp-4681-O. This will connect the flex to the top of the stove.

If you look at the pictures for the extend-a-cap you will see that it includes a cap, storm collar, clamp, and base. I used the included clamp to support the installed section as I pop riveted the next section on. Then loosen the clamp, lower and repeat.

If you dont own a pop rivet gun, they are in expensive to buy at Sears, HDepot, or Lowes. I would suggest buying a box of pop rivets, use some thin scrap metal with some 1/8" holes drilled in it and pop rivet it together so you understand how it works( it's very simple really) before you put your chimney sections together.

 

[gpcollen1]

Insulated rigid double wall here, with 5' of flex through the smoke shelf. Love the rigid.

Me too, but it is more expensive for sure. About 15 ft of Duraliner in one chimney and 25 ft of flex in another.

 

[begreen]

Regular rigid liner is much heavier gauge than flexible liner. It is typically about 24 ga (.024") and very tough stuff. Good flex liner is about 36 ga or .006". It works very well but should be brushed with a gentler polybrush.

Class A pipe is not used for chimney liner.

Rigid Duraliner is a sweet install and what I would recommend. It has an inner 27ga (.016") liner, then insulation, then a rigid outer shell. I like the enclosed insulation and easy installation. The Duraliner product line is more expensive, but offers lots of options to cover almost any installation.

 

[Benchwrench]

Thank you very much for that information.
I will look into rigid "duraliner".

Another question regarding rigid...
Are there any manufacturers of rigid who use a "continuous weld" or are they all spot welded along the seam?
where in the world can I find the proper insulation for rigid? meanwhile, I'll keep looking

finally,
Which brings me to the installation aspect of the insulation,
How does the insulation "stick" or stay on the pipe through out its lifetime? if not the rigid "duraliner" product?

edit:
rigid Duraliner seems to be a serious contender for a liner, very sanitary install, no need for an outer wrap.
so I edited this post a scoche.

I was thinking that all rigid was a single wall construction 24 ga. pipe that needed a wrap (with the exception of rigid "duraliner") that it will need to be wrapped.
I am still keeping my options open.

thanks guys.
Bench

 

[Benchwrench]

I've decided to use DuraLiner rigid and I've chosen their heavy duty flex for the connection between stove and rigid. (evidently the have proprietary flex connectors all ready made up) This particular flex is their old tried and trued 4 ply .016 that's also got my vote (as thicker is better in my book) . It's my understanding that this flex is specifically for the rigid DuraLiner product and there are no raw ends to deal with. One end of this pre-cut flex has the rigid type connection, the other end accepts the stove collar connector that mounts on top of the insert.
Also there is a special insulation that CAN be used on it and of course I will be insulating it as well.

At least the aspect of which liner is best for my needs has been dialed in.

Thanks to all who contributed in this thread

helping me choose rigid.
I believe going with rigid has merit, and to narrow the choice down to what seemed like a whirlwind of manufacturers and various product lines.