Wrapped vs. poured liner insulation

[chipster96]

I'll be building a brick, outside-wall chimney soon for a Regency insert.

There will be a stainless steel liner (no reason for double wall, right?).

How do the poured and wrapped liner insulation compare?

Are there other alternatives, could I just pour vermiculite down around the liner?

 

[edthedawg]

When you said "poured" the first time (vs. wrapped) I thought you meant vermiculite. You mean the cement-type pouring? I couldn't see going to that trouble w/ a new brick chimney. If you build it as a chase and drop in an insulation-wrapped 6" SS liner, that oughta do ya. You're not going to the trouble of building in all the fireplace / smoke-shelf features, are you?

I think a poured vermiculite insulation is a fine idea, but you need a good blockoff plate, AND you can pretty much never ever remove that plate. If something fails w/ the liner and you need to replace it, you have a massive cleanup effort on your hands.

And it does beg the question - could you build in Class-A / prefab into this? sounds like a good idea - it's what I'd be looking at if I was in the market to add a new ground-up chim somewhere.

 

[chipster96]

Yes, the concrete type is what I meant. No, there'll be no smoke shelf or any of that.

By prefab, you mean an elaborate liner, like a double-walled, insulated SS pipe such as Sealkirk? Or something that includes masonry?

If my flue liner is going inside a new brick chimney, is a double wall desirable, or overkill?


Thanks oodles.

 

[edthedawg]

Well i'm thinking of something like new construction - you see a lot of chimneys now w/ siding on them, as opposed to more costly masonry chimneys. Those sided chimneys are just chases really, w/ pre-fab (Class-A) chimney piping inside. Brands include Selkirk or Simpson Dura-Vent. It sounds like you're doing the more costly brick-faced chase, as opposed to the modern convention of sided chases.

Depending on how much space you have to work with, you could consider adding sheets of mineral wool insulation (comes in 4" thick sheets i think, is easy to work with, and is not very expensive for a large pack of it) inside your brick chase, and not touching the Class-A pipe inside. That would really be the optimum solution I'd start with. But I've spent about the time to type these two posts thinking about it very hard

FWIW - I hate those stupid sided chimneys. I applaud you building an authentic-looking brick chimney. Make sure you include ample clean-out access.

 

[chipster96]

Make sure you include ample clean-out access.

Hoo boy, one question leads to another. Do you mean by this that the base of the pipe should be easy to reach? Will the insert have to come out for chimney cleaning, and somebody have to get at the base of the flue liner? Is a four foot high cavity enough?

Also, I've pretty much discounted the possibility of a clay flue liner because of the danger of cracking, and the near-impossibility of ever replacing it. Am I thinking right?

 

[edthedawg]

Oh. Duh. Regency Insert into a brand new chase... No cleanout - the pipe runs right down into the top of the insert. More or less.

I was thinking of how you'd set up for an "out-the-back" pipe from a freestanding hearthmount stove.

Now, about the 'more or less' above. The cavity where the stove lives will have a sheetmetal blockoff plate atop it, built to be removable in the future by pulling the stove and removing a few screws, and the Class-A pipe descends thru it. Assuming you have your clearances and footprint all laid out properly, one would envision you'd run your Class-A pipe down the chase thru that sheetmetal blockoff plate, and you'd arrange things so that the pipe very nearly - if not perfectly - aligned w/ the outlet collar on top of the stove when it's sitting fully "home". You'd only need a short flexible connector piece to merge the two (stovetop exit collar w/ bottom of Class-A chimney pipe).

So your might build some sort of metal lip into your brickwork, into which you can drill and put some sheetmetal screws to hold the plate. Plates very rarely need to be removed. less frequently than pulling the stove. But I wouldn't envision needing cleanouts or clay liners here. Class-A pipe has (i think - check for yourself) a 2" clearance requirement to all combustibles. If you're building it into a brick chase, I'd like to think you'd easily meet such a requirement. And if you add mineral wool insulation between the two, all the better...

 

[BrotherBart]

i dont think u can pour vermiculite=if liner fails & gets a hole in it, vermiculite would pour into chimney & plug it...i think. i'd use sections of ss pipe liner & insulate with mineral wool as the chimney is built

Take another hit off the bong Pook. Poured Vermiculite is used to insulate liners all the time. The only thing is to make sure there is good sealing at the bottom so the stuff doesn't pour out.

 

[edthedawg]

*snicker* yeah the pouring out problem is the biggest reason I don't bother insulating mine. But it's the center of three flues on a massive interior chimney dating back to 1885, so insulation doesn't seem to be a real big problem.

But gawd help me if i had to contend w/ a 36' column of vermiculite dumping into my living room. UGH.

 

[BrotherBart]

But gawd help me if i had to contend w/ a 36' column of vermiculite dumping into my living room. UGH.

I believe that happened to the Webmaster Craig when he owned his stove store.

 

[BrotherBart]

BUT IS IT CODE/LEGAL. WHERES ELK?

Yes it is. And you know where Elk is. Go ask him.

 

[BrotherBart]

BUT IS IT CODE/LEGAL. WHERES ELK?

Yes it is. And you know where Elk is. Go ask him.

already did & waiting still the scenario seems probable so i predict future code will not allow besides dont u need an airspace between the kwool & the chimnyblock? when using ss liner.

No.

 

[johnn]

chipster,,Gp up top to "HEarth.Com Quick Navigation" ,,pull down Menu and go to" Main Informational Articles",,You will find an article on Block Off Plate (pics)
Single wall flex with wrap insulation installed during construction should be easy and effecient. You could as mentioned add an insulation board to the chase at your option.Top exhaust stoves, and inserts will be easy to sweep, as all the waste falls into stove fire box, once the upper baffle is removed. Rear exhaust stove would require being able to access a clean out drop,,,as the waste material wont be able to fall into the stove.

 

[gibson]

i dont think u can pour vermiculite=if liner fails & gets a hole in it, vermiculite would pour into chimney & plug it...i think. i'd use sections of ss pipe liner & insulate with mineral wool as the chimney is built

Take another hit off the bong Pook. Poured Vermiculite is used to insulate liners all the time. The only thing is to make sure there is good sealing at the bottom so the stuff doesn't pour out.

hehehehehehehe!

 

[summit]

Vermiculite around your liner is no longer to code in Many places, because if you get a split on the lining if will pour out into your liner like sands in a hourglass. If you are going to the trouble to build a fireplace for an insert, you should still line it w/ clay tile (probably an 8" round or 11x11 square) and make a proper smoke shelf.... you may not own that house forever, and the next owner may want an open functioning fireplace instead of a regency insert. Once the chimney is complete, dump a roll of 6" flex liner down thru and connect into the insert. With the clay tiles built into it, i don't think you would need to bother w/ the insulation from a safety perspective, but since its an outside chimney you may want to wrap it with the mineral wool (a 1/2 thick blanket should suffice..25' for @ $250) to keep the flue warm when the masonry is being pummeled by below zero temps, which can adversly affect your draft. The tiles shouldn't have any issues w/ cracking, since the stainless liner will take all the abuse, and this whole setup will be a very modular thing that can be removed and reinstalled easilly. Just m,ake sure the tiles you install are large enough to accept the 6" liner and insulation it will be around 7-8 inches in diameter when all is said and done

 

[BrotherBart]

Vermiculite around your liner is no longer to code in Many places, because if you get a split on the lining if will pour out into your liner like sands in a hourglass. If you are going to the trouble to build a fireplace for an insert, you should still line it w/ clay tile (probably an 8" round or 11x11 square) and make a proper smoke shelf.... you may not own that house forever, and the next owner may want an open functioning fireplace instead of a regency insert. Once the chimney is complete, dump a roll of 6" flex liner down thru and connect into the insert. With the clay tiles built into it, i don't think you would need to bother w/ the insulation from a safety perspective, but since its an outside chimney you may want to wrap it with the mineral wool (a 1/2 thick blanket should suffice..25' for @ $250) to keep the flue warm when the masonry is being pummeled by below zero temps, which can adversly affect your draft. The tiles shouldn't have any issues w/ cracking, since the stainless liner will take all the abuse, and this whole setup will be a very modular thing that can be removed and reinstalled easilly. Just m,ake sure the tiles you install are large enough to accept the 6" liner and insulation it will be around 7-8 inches in diameter when all is said and done

You have me curious. What are some of the "Many places"? And how do you address the zero clearance to combustibles certification for liners, most of which specify that it is required by the listing?

Ain't nitpicking. Just trying to learn.

 

[johnn]

You still out there chipster?? I believe with enough research and questions, I could manage a masonry project in the format you are describing. But for a functional fireplace, I`d definitely hire that out. The poured vermiculite I feel would also work and I believe they wet it some to increase density during pouring. Being messy for future replacements or repairs is a given, however if you were to utilize a clay liner I dont feel it would be an unsurmountable mess. It wouldn`t be a huge volumne needed to fill the void. I thought I had read at one time, that there should be a 2" void between the liner and any obstacle, combustible or otherwise, but I never seem to read much on that, so I could have misread or misunderstood. It`s difficult to visualize these flex liner upgrades, meeting that 2" requirement when installed into existing chimneys.

 

[edthedawg]

2" is the clearance to combustibles req'd for class-A / prefab solid chimney pipe. a plain liner should have more clearance.

I just can't see going to the trouble of building a brick chimney / liner opening, and then doubling the complexity to add the smoke shelf and flue tiles, and THEN bodgering it up with a plain liner. If you have the luxury of building new from ground up, put in nice new solid pipe and rockwool as you go! F the next owners - make it very clear that they have a great insert location there - it's NOT for an open fireplace. period.

yes, i made up a new word. bodgering.

 

[edthedawg]

ok so it wasn't a new word. maybe i heard it before, 'cause i seem to have used it exactly properly:

'This comes to an important point, bodgering is bad. If you don't know what the word bodgering means, its essentially a term for forcing the square peg to fit in the round hole. Its a term I like to use a lot when describing indie and mod development because somewhere along the way everyone does it as a quick solution. The problem is that this almost always costs you more in the end. Sure you might have a product, but do you really think that anyone will appreciate seeing an ungodly sight due to the result of bodgering? No we don't. In fact when we were younger bodgering something usually resulted in some "special time" for the individual, so I am completely floored when we do this in our productions and think that it's all going to be OK. Everyone will notice it from a mile away, it will feel funny and odd and just ruin the overall product that you are presenting as people will begin to question that ever important "suspension of disbelief".'

(from http://fosters.realmwarsgame.com/archive/2005_06_19_archive.shtml)

 

[chipster96]

Thanks everyone for the highly informed discussion, I got several key bits of info.

Until I change my mind, I'll be going with a single-wall, 24g ss liner wrapped in rockwool.

I am also now considering building the chamber roomy enough so that someone could build in a smoke shelf and convert to an open fireplace. Or not.