Tell me about chimney liners

[Steve NW WI]

I'm putting in a new stove in about a month. I got to thinking about making some chimney improvements while I'm at it. Ideally, a triplewall setup going up through the house would be best, but house layout makes that difficult at best without some remodeling. I'm thinking a SS liner in my existing chimney is the next best option, but I've got questions.

First, the setup. I have a block chimney with a 7" square clay tile liner that's freestanding alongside the house. A piece of clay tile runs out through the block wall of the basement and to the chimney about 1' below ground level, and there is no cleanout on this chimney, I have to shove the shop vac down there after cleaning to suck out the soot/creosote. It's in good working condition, and actually drafts well 98% of the time. On the downside, I have to clean it between 3-5 times a season, even with dry wood. It's about impossible to keep warm enough to stop creosote formation without overheating the stove.

Here's a layout sketch, just for visual:

So, my questions. Smooth or regular flex liner? Solid liner (non flex)?

Poured insulation or wrap?

Are there any kits out there that I could add a 3' section of triplewall to the top of? I think I'd benefit from being a bit higher than it is.

Would it be a good idea to fill the space in the bottom of the chimney below the tee with sand? Does the bottom of the tee have a cap on it, or is it open?

How much benefit will I see from an insulated SS liner? I'm kinda cheap, and if I still need to be up there cleaning it all the time, I'll save my money and spend it on something with a better return, like a couple more new windows.

I'm sure I have more questions I just don't know to ask, but that's what I can think of right now.

BTW, checked one chimney site, 15' x 6" stainless flex setup with poured insulation was about $450 there, haven't shopped around too much yet, is this a reasonable price? Forgot the brand right offhand, but could look it up again.

 

[stihly dan]

That sounds like a great price. Is the poured insulation the solid type? Sorry don't know the actual name for it. I looked into that up here a few yrs ago, and it was expensive, at least 3 times that. A new liner for better draft and an EPA stove, with your wood and knowledge, probably would not need to clean the chimney anymore.

 

[laynes69]

I choose a rigid liner because it drafts better, thicker material and just more durable. With that said, many choose flex liners and don't have any problems. If your chimney is in good shape now, no cracks in existing liner or missing tiles, you don't need insulation. With it being an exterior chimney though it wouldn't hurt. Your tiles are 7x7 and a 6" flex liner is around 6 5/8" or they say the size of a paint can. I used vermiculite because it's cheap and works but it's not a material listed for use with just about all liners. Some use vermiculite, others use perilite. Just be sure there's no holes, or it will pour out. That's the cheap route, but there's an insulated concrete mixture that's listed as well as an insulation blanket. You may not have room for insulation if you choose a flex liner, the only possibility would be pourable. The space below the tee, I would backfill. Just make sure to order a cap for the tee. We eliminated our bottom cleanout and I was worried about it, but there's been no issues. Each sweep there's very little creosote to worry about since upgrading. There is a liner that's rigid that's either double walled, or has some sort of snap lock insulation. The cost would be higher, but I believe it carries a lifetime warranty and would give you everything in your space as well as better draft. For sure a liner would be the way to go, along with the new stove.

 

[Fred Wright]

Steve, if I had the option I'd go with a solid liner if possible. Flex is OK but a solid flue liner is easier to clean. The tee at thimble, if used wouldn't need a bottom cap (couldn't access it inside the chimney anyway) but you'd probably have to install a cleanout door beneath the thimble if you used a tee.

The tee with cleanout cap is used primarily with through-the-wall manufactured chimney installs. We did a lot of research before investing in a manu chimney. As far as I'm aware, there's no manu chimney specs for coupling with and extending an existing masonry flue. If you wish to add height, a mason could give you the poop you need on that. Catch him or her in the summer when work slows down.

With a 7x7 flue, there may not be room for pipe insulation. A poured insulation would be your best option. Like Laynes says, there are alternatives.

The advantage of an insulated flue liner ~ the liner or flue pipe heats faster and stays hot longer. This in turn reduces creosote buildup. With your chimney being exposed to the outdoors, an insulated flue pipe would mean fewer trips to the roof for cleaning. It helps your draft, too.

You may save by having the work done during summer when business is slow. We had ours installed in July and the contractor gave us a break for paying by check.

Hope it helps.

 

[chadihman]

Solid ss liner and a poured insulation is the best but expensive. A new stove with that setup should not accumulate creosote. Should last a lifetime and withstand a chimney fire

 

[TreeGuyHR]

Hmmm

I'm thinking of tossing the pellet stove and putting a wood stove in the house.

Background:
I have a weird old house -- when I bought it in '99, it had three different flues (in a small two bedroom). I got rid of one rusty metal one, kept the brick chimney (block in the wall on the main floor, center ofthe home, brick through the roof) and the pellet stove (but replaced its flue with a taller one for better draft and clearance from the house). Another problem with the pellet stove is it is in an outside corner, in a part of the house that hasn't been remodeled yet (likely no insulation or maybe some burlap or cardboard!). So it never has heated the house very well.

Plan:
Inspect the chimney -- what might I find? What probably needs to be done?

I had it re-pointed and flashed when I replaced the roof. Also had it tied in -- it was free standing, and just supported side to side by the old flashing. There is a wall "tin plate" entry into the block portion for a wood stove at about 4 1/2 ft. off the floor and about one foot from one wall --- kinda close.

What do i do about the location of the entry for the stove pipe? I am thinking that I will need to put tile on the wall, backed with concrete board, and double-walled pipe because of the location. Would't that sacrifice a lot of heat output (instead of single wall pipe)? Probably I can find a modern stove with a blower for more efficiency.

 

[cheeves]

I'm putting in a new stove in about a month. I got to thinking about making some chimney improvements while I'm at it. Ideally, a triplewall setup going up through the house would be best, but house layout makes that difficult at best without some remodeling. I'm thinking a SS liner in my existing chimney is the next best option, but I've got questions.

First, the setup. I have a block chimney with a 7" square clay tile liner that's freestanding alongside the house. A piece of clay tile runs out through the block wall of the basement and to the chimney about 1' below ground level, and there is no cleanout on this chimney, I have to shove the shop vac down there after cleaning to suck out the soot/creosote. It's in good working condition, and actually drafts well 98% of the time. On the downside, I have to clean it between 3-5 times a season, even with dry wood. It's about impossible to keep warm enough to stop creosote formation without overheating the stove.

Here's a layout sketch, just for visual:

So, my questions. Smooth or regular flex liner? Solid liner (non flex)?

Poured insulation or wrap?

Are there any kits out there that I could add a 3' section of triplewall to the top of? I think I'd benefit from being a bit higher than it is.

Would it be a good idea to fill the space in the bottom of the chimney below the tee with sand? Does the bottom of the tee have a cap on it, or is it open?

How much benefit will I see from an insulated SS liner? I'm kinda cheap, and if I still need to be up there cleaning it all the time, I'll save my money and spend it on something with a better return, like a couple more new windows.

I'm sure I have more questions I just don't know to ask, but that's what I can think of right now.

BTW, checked one chimney site, 15' x 6" stainless flex setup with poured insulation was about $450 there, haven't shopped around too much yet, is this a reasonable price? Forgot the brand right offhand, but could look it up again.

PM rooftopcrew!!! Expert on this!! Has been doing this for a long time!! Good guy, AS member, and friend of mine!!

 

[bayard]

line it

i did mine this summer. get the half inch wrap and insulate it your self.then wrap it with the flex wire or welding wire . big improvement ,you want to keep the pipe as hot as possible.k

 

[chadihman]

i did mine this summer. get the half inch wrap and insulate it your self.then wrap it with the flex wire or welding wire . big improvement ,you want to keep the pipe as hot as possible.k

That sounds like a nice setup but that probably will not fit in a 7" square chimney. I installed 6 ft sections of solid down my 7'' square and had a hard time pushing 24' down a not perfectly straight chimney. The liquid insulation can be poured down around the pipe with a home made funnel made from cardboard.

 

[Steve NW WI]

Thanks guys. You've about got me talked into a SS flex liner with poured insulation. The site I got my $ estimates from was Rockford Chimney supply. The insulation is vermiculite based. I checked prices on smooth walled flex, about $150 more, and solid which I ruled out pretty quickly at more than double the price of flex.

Finaces permitting, I'll put it in when I swap stoves, otherwise it might wait till summer. I plan to DIY it, looks pretty straightforwad and easy with a little assistance.

Cheeves, I sent your friend a PM asking for his thoughts, but I see he was last here back on Halloween.

Anyone think the tip up rain caps are worth the money over the plain screw on ones? I'm having a hard time convincing myself I need one.

 

[taskswap]

I have an exterior chimney, too, and you're right - it's a pain to keep warm. I went with a flex liner because whoever laid my tiles didn't lay them straight - they were all shifted 1/2" here and there, and no way would a straight liner have ever made it down. As it was, I had to knock out four bricks in two "strategic" spots to get into the side of it near the bottom to get around a really bad ledge. Took all day with my FIL.

Given that, no way was it going down with an insulation wrap. It's a 6" liner in an 8x13 rectangular clay tile flue, but as others have noted it's always a little wider, especially if it's corrugated - and I was losing an inch here in spots where the tile offsets were. So I used a pour-down insulation, and couldn't be happier.

I'm not shilling for the company, but by way of price-reference I got my liner from Rockford Chimney for $420 (not counting shipping) for a 30' length plus cap and tee, and four bags of insulation from the same place for another $300. I picked them because they have a "custom" shop if you need a weird shape fabbed - although I never ended up using the service so I donno if they're any good. I remember measuring the wall thickness with a caliper and comparing it to a friend's "high end" kit and finding it the same (I didn't write it down). By the way, when they say "flex"... this stuff ain't like dryer hose. It took both of us holding it just to straighten it out. It's stiff as he**.

That pour-down insulation is an odd beast. I mixed mine on the ground and regretted it. Getting it on the roof was a pain and took a lot of trips. I should have used a rope to bring a hose up on the roof. Could have cleaned my gutters too! :rolleyes2: It's a pain to mix in big batches, but if you do only a quarter-bag at a time, it goes pretty quick. I think I spent all of three hours on that part.

So... I have an exterior brick chimney and the boiler is in the basement plus other factors - basically everything that makes a chimney perform poorly, and yet I'm getting very little creosote buildup and decent draft. I have to say, I'd do it again in a heartbeat. Sure is easy to clean...

 

[Campbell]

Rockford chimney also sells kits and liners on ebay. If i remember correctly they were cheaper on ebay than the price listed on their website.

 

[Steve NW WI]

Thanks again, and especially to taskswap, it's always good to hear from someone with a similar setup.

Del, thanks for the link for the Thermix, it's about half the price elsewhere than what Rockford was selling theirs for. Going to be doing some shopping around on the whole works before I buy, looks like prices are like stoves, all over the map and you've got to look for a decent deal.

I dropped off some rep where I could.

 

[FLHX Storm]

First, don't take my word as gospel here because I don't know an awful lot about this sort of thing, but enough to have gotten my system set up and working well.

+1 on the vermiculite! My reason for using it wasn't the cost, but rather "What If?" What if I needed to redo something, what if I needed to replace the liner for whatever reason? I wouldn't be able to remove it had I used a cement like the Thermix. Since the main ingredient in the Thermix is vermiculite, and those insulating blankets for wrapping the liner also contain vermiculite, I figured why not just use raw vermiculite and be done with it. I purchased all that a local garden shop had (also can be used as a soil amendment which works better that pearlite BTW)

One thing I have noticed is the only part of the liner that has developed any creosote is the top part of the "single wall rigid stainless steel liner" where it hasn't been surrounded by vermiculite when I was cleaning the liner. With that, I would highly recommend insulating the liner be it the Thermix or Vermiculite.

I had read on some sites that if your relining your chimney with a stainless steel liner that it wasn't necessary to insulate it if it's being used inside a regular brick n mortar chimney. Other sites recommend using "their" insulated blanket. Well, I wanted more than just a half inch of insulation. Why pay as much for the blanket as for the liner itself? I'm not cheap by any means, but something about that just irritates me to death.

Like I said, since the main ingredient in the blankets and thermix is vermculite, why not just go with straight vermiculite. The only drawback is, as another poster put it, be sure to seal everything or it will pour out through that opening. I used the Great Stuff foam insulation to seal up the area by the clean out at the bottom of my chimney while still giving me access to that clean out.

I used a single wall rigid stainless steel liner for in the chimney and a double walled black flue from the wood stove into the chimney and have no issues.

One thing to also keep in mind is "Combustion Air." The more modern stoves have an outlet you can hook an aluminum kit to that you run to the outside. DO NOT USE PVC! Whether your home is well insulated and well sealed or not, I would recommend using the outlet to get outside combustion air. That way it will draw cold air from the outside rather than using inside air which has to come from somewhere which means it is pulling outside air into the house from wherever. Or if the house is well sealed, the fire won't burn well for starters. It will also use up the oxygen inside the house if your successful at getting the fire going. One of the first signs of oxygen depletion in the home is feeling light headed.

Another thing I haven't seen mentioned here is to use the proper sized liner. Match the liner to the opening for the flue at the top of the stove. If it's 6 inches, use a 6 inch liner throughout. If it's 8 inches, go with an 8 inch. You'll get a better draw making your stove more efficient. Going smaller or larger downgrades the efficiency of your wood stove. N who doesn't want their system to operate as efficiently as possible?

I can't say anything as far as which type of liner to go with (flex or rigid) because I have limited experience and then only with the rigid liner. Also keep in mind, this is my first time ever using a wood stove and installing a new liner in the chimney which I also did all by my lonesome.

 

[taskswap]

Like I said, since the main ingredient in the blankets and thermix is vermculite, why not just go with straight vermiculite. The only drawback is, as another poster put it, be sure to seal everything or it will pour out through that opening. I used the Great Stuff foam insulation to seal up the area by the clean out at the bottom of my chimney while still giving me access to that clean out.

It shouldn't cause any harm using straight vermiculite, but the "other" ingredient in the mix is portland cement, and its job is to make the mixture hard. You can easily break it up to remove it if you want to later, but it does harden into a stiff mass. It's supposed to do two things. First, it supports the liner, keeping it centered in the chimney as it expands and contracts over time. I think with rigid that's no biggie, but with flex liner you wouldn't want it shifting around so that one part actually touches the masonry and gets cold. Second, if you do get a pinhole somewhere, air isn't going to go anywhere because the portland cement makes it non-porous. I personally think that risk is very small but what the hey...

If you wanted to save money you could probably make the mix yourself - I think I read somewhere that the ideal ratio is 6:1 vermiculite to cement (YMMV). I dunno what each component costs separately...

That Great Stuff sure is... great.:msp_biggrin:

 

[laynes69]

I wanted to use thermix, but was recommended against it from the maker of our liner, and the local sweeps. A rigid liner expands differently than a flex liner. I've watched our liner rise when hot and it expands vertically, not horizontally. Either vermiculite or perilite allows for the expansion. We did downsize, however our chimney is 32' tall so it was fine. Thermix is made with either vermiculite or perilite, where the blankets are made of ceramic wool. What to take into account if thinking of using vermiculite or perlite, both can and will absorb moisture unless treated. So everything must be tight. We had a custom stainless topper made for our chimney to keep out the weather.

 

[KindredSpiritzz]

Ok, so if i read this all right. You guys install a stainless steel liner inside a brick chimney and then pour or wrap insulation around the entire length of the liner? i never heard of that before. What happens if you need to replace the liner at some point? Have to take all that insulation back out? My liner/chimney isnt insulated so im wondering if thats something i should be looking at.

 

[taskswap]

Ok, so if i read this all right. You guys install a stainless steel liner inside a brick chimney and then pour or wrap insulation around the entire length of the liner? i never heard of that before. What happens if you need to replace the liner at some point? Have to take all that insulation back out? My liner/chimney isnt insulated so im wondering if thats something i should be looking at.

Yes, that's right. You shouldn't need to replace the liner - the liner "becomes" the new chimney, and it's thick stainless steel so I wouldn't be surprised it if had a lifetime in the 100+ year range. I suppose repeated chimney fires could weaken it, but it's very durable.

But if you DID have to remove it, it would be no problem. I would use a chimney sweep rod to break up the insulation around it (I have the pour down kind, as noted above - not Thermix, though, I have the stuff Rockford sells), and then a shop-vac with a long hose to suck that stuff out. Then the liner would pull right out, drop in a new one, re-insulate, and you're good to go. I hope I never have to do it again - but now that I know how, I bet I could do it in an easy weekend.

The idea behind these systems is that the liner "becomes" the new chimney - everything around it is just structure and visual appeal once you install one. The insulation is a HUGE help. It does two things - first, it helps improve the draft, because the air in the flue stays warm all the way up. Second, it reduces creosote buildup - for the same reason.

I know there are those that swear by those wraps, and maybe they're even better. But I'm personally glad I used the pour-down kind. Fussing with a liner is kind of a pain, and I would have been cursing a lot more if I had had to try to avoid shredding a flimsy wrap at the same time. Of course, I have a narrow rectangular clay tile flue with offsets from poor masonry work. I suppose if you had a huge square flue with lots of room the blanket would be better - you'd have plenty of room for it, and you would have needed a LOT more pour-down insulation. YMMV.

 

[KindredSpiritzz]

you got a link for those think stainless liners? Only ones i have ever seen are like glorified dryer vents i cant see lasting 5 yrs much less a lifetime. I'll have to look into that for next year. Info on the insulation would be great to if you had a link handy.

 

[taskswap]

you got a link for those think stainless liners? Only ones i have ever seen are like glorified dryer vents i cant see lasting 5 yrs much less a lifetime. I'll have to look into that for next year. Info on the insulation would be great to if you had a link handy.

I got mine from Rockford Chimney Supply, Chimney Liner, Flue Liner, Covers and Caps - Stainless Steel | Rockford Chimney Supply. As noted above, you can get better deals on eBay sometimes and save a few bucks. They sell both the liner kits, individual parts, and both types of insulation. I am NOT shilling for them - I'm sure there are other vendors out there, and can't say whether they're better or worse. But I did have a good experience and their shipping was fast, at least to CT. I have the instructions here on my desk - it looks like the product itself is made by National Chimney Supply, which has four locations - two in MD, one in VT, and one in IN. (In case you care.)

This stuff may look like dryer vent hose, but hold a section in your hands. It doesn't feel flimsy at all - it's very stiff, and actually kind of a pain to bend. I have a 2' length of it left over with a bit of a curve left in it, and for giggles I just tried to bend it straight and couldn't do it by hand. It's not as stiff as hard copper pipe but stiffer than soft copper. And it takes a lot to eat through stainless - I have no doubt this stuff is going to last decades, not years.