Are there any manufacturers who do an ovalized pre-insulated liner? I've been looking but haven't seen one. I'm in the same situation and need to run 23' of liner through my 8x12 (7x11 inside) terracotta-lined chimney. I can see a few offsets in the clay liner blocks not being perfectly aligned so I expect it'll be a bit of a squeeze in some spots. Would wrapping a standard ovalized liner with insulation be a better way to go for the space? Are there advantages or disadvantages to different insulation methods in this circumstance?
Oval Chimney Liner Insulation
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The DuraLiner system has oval lengths of insulated pipe. It's a rigid pipe lining system.
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Thanks, are these for running the entire length of the chimney? All of the usage examples on that site show transitioning to a round liner once past the damper.
That depends. Is this for a stove connection via a wall thimble into the chimney or a fireplace install of an insert?
This is an open fireplace conversion install. I'll be putting a Morsoe 7110B in an existing open masonry fireplace
The transition from oval to round occurs just above the damper area, typically with a flex section made to do this transition. The flex section gets wrapped in an insulation sleeve.
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6" x 36" DuraLiner Oval-to-Round Flex Chimney Relining Pipe - 6DLR-36ORF
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I am a bit confused. Because my chimney is 7x11 inside, I was thinking I needed an insulated ovalized liner to fit the space and run the length of the chimney. Or am I right in thinking this but looking at the transition piece upside down, and really I'm converting from an oval inside the chimney to round inside the fireplace? Sorry it's taking me a minute to grasp. I was originally looking at an ovalized flex liner and thinking I'd wrap it with an insulation blanket, but the duraliner is interesting.
I think I paid roughly 1500 back in 2020 for the rigid oval duraliner system to do mine. I think I had 4-48” sections, 1-12” section, 1-48” flex oval to round and then the top plate support system. Which is roughly I think it was 21 feet in total length of the pipes.
True. The main issue is mortar squeeze out at that particular spot. I imagine I can break some of that out, but flexible might be easier to work through there?
![[Hearth.com] Oval Chimney Liner Insulation](https://www.hearth.com/talk/data/attachments/318/318071-2732d2c75c8e46815cb769859d72c884.jpg?hash=wzzsWrIAOJ "[Hearth.com] Oval Chimney Liner Insulation")
I have the same size clay liner in my chimney. Had no issues with the rigid duraliner. Just use the flex section at the end that goes from oval to round to snake down from where the clay ends down through the cut out damper to your fireplace. I even installed the whole thing by myself
The mortar ooze only looks like about an inch. 6" DuraLiner is 4 3/4" x 7 3/4" so that should leave an inch or so to clear. If it's easy to knock it off with a pole, even better. Duraliner works for straight runs. An offset in the flue will need flex.
Is that DuraLiner enough for the 6" flue requirements? I ask because I ran the conversion on this site (https://www.rockfordchimneysupply.com/pages/chimney-liner-size-calculator-and-selection-guide) and it shows to maintain the 28 sq in volume of a 6" round, I'd need a 8.15" x 5" ovalized liner. These dimensions are close to the duraliner, but I know the inside diameter of the duraliner must be smaller because it's insulated, cutting down the volume even more.
Yes, there are several hearth members running stoves on them. With 23' of liner the insert should draft well.
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