Chimney liner: solid or flexible?

[Ken45]

We are getting a new stove (PE Summit) that will sit in the existing masonary fireplace. The current chimney is double 12x12 clay. We need a single 6" diameter flue.

Especially since I have to do a bit of an offset from the one flue, the stove dealer (who doesn't do installs and isn't too knowledgeable IMO) is suggesting SS flex line. That sounds simple. The pipe length will be about 13'. Is it okay to have it just dangling in the existing chimney?

I've also thought about backfilling with perlite or vermiculite to provide some insulation and block off the other flue.

I saw one message where someone was using flexible line at the bottom and then mating up with double wall. Would that be better, or should I consider going solid all the way and using a couple of 45's to get the offset I need?

A long flex liner seems like it would be difficult to clean

What are the pros and cons of flex vs solid liner?
Thanks

Ken

 

[jtp10181]

If the offset is at the bottom you could use the Simpson Duraliner system which you can attach a 60" flex at the bottom. It all goes together with pop rivets. Easiest install will just be a SS flex liner kit. Yes, it can just dangle. Safest would be to insulation the liner top to bottom.

 

[webbie]

Chimney sounds a bit short. You might want to run the liner a couple feet out of the chimney and encase it with one of my little castings:
http://www.extendaflue.com/cast.html

Rigid liner drafts better, is easier to clean and should last much longer, since it 3X to 4X as thick. 24 gage is the typical thickness of rigid liner...I think that is
.024
while most flex liner is:
.006

There are many different grades of flex also. Some of the best is Ventinox, which is seam-welded. Many lesser brands are just pressed together.

Rigid pipe is usually electron welded continuously these days, which is really a good method....Heat-Fab is one well known brand.

To get to the unit with an offset, you can either use an adjustable el or - many use a short piece of flex for the last connection closest to the stove.

 

[jbrown56]

Hi Ken, I installed a 6" rigid liner into an interior 8" x 12" clay liner. My stove exhaust into the chimney which is 20' straight down. For me, it was a simple decision to choose rigid over flex. I thought it would be much more durable and easier to clean. The id of the clay liner is 6 3/8" x 10 3/8" and was snug going in and took about four hours to complete. You should have plenty of room in your 12" x 12". I didn't insulate my liner as there was not enough room and the existing clay flue is in good shape. I wasn't aware at the time I could've poured loose fill insulation. If I had, I would have insulated the liner. The pipe, tee, cap, storm collar and clamp was about $600. The rigid is more expensive than flex, but, I think it's worth the extra money. I hope this helps.

Jim

 

[Ken45]

Thanks all for the replies. We actually got the stove delivered yesterday and I kind of like it sitting in the room instead of putting it in the fireplace, it looks so nice there and I can just imagine it sitting there radiating heat! Wife still thinks it should go in the fireplace

This is supposed to be the dining room but it's too small to use it that way and it's in the middle of an open floor plan. We plan to turn it into a "sitting room", looking forward next winter to sitting in there by the fire, watching the snow on the hillsides

Ken

 

[Lasher]

I recently installed an Avalon Olympic insert into my fireplace and used a rigid/flex/elbow combination. If you search on my username, you will find a detail story of my install.

A few highlights...

I went with Duraliner rigid for the top 20 feet. This is double walled and insulated. (my flue is 12x12) I then used the "rigid" flex liner for the bottom 5 feet. I found that my insert exit hole could not line up with the flex liner so I installed 2 45 degree elbows to connect the insert to the liner. Worked out great. My draft is awesome and I will be cleaning the liner for the first time in the coming weeks when burning season is officially over.

As for flex vs rigid, you can search and read for days (I did). But to me if you can go rigid, then use rigid. The extra cost is worth it. The difference between the double walled rigid and the "rigid" flex liner is easy to tell when you have both pieces on hand. And if I went for the regular flex liner I would have been even more shocked at the difference.

 

[DriftWood]

Thanks all for the replies. We actually got the stove delivered yesterday and I kind of like it sitting in the room instead of putting it in the fireplace, it looks so nice there and I can just imagine it sitting there radiating heat!

Ken

Go for it pull it out into the room you will not believe the heat you will get off it. I did that with my first home burned 24/7 never used the furnace. Single wall pipe to the ceiling will add output BRUs like you would not believe.

I was not able to do this in my present home. The lack of a exposed single wall pipe and a exterior lined chimney are a waste of heat, avoid it if possible.

This is what I have now.
HearthStone Heritage break in fire!!
https://www.hearth.com/talk/threads/3106/