Importance of insulating the liner in a masonry chimney

[jankdc]

I'm looking to install a wood stove into my fireplace. The chimney is 8"x10" and 25-30 feet long.
All of the new stoves we are looking at take a 6" flue. None of the installers that I talked to mentioned insulating the liner. When asked, one quoted me $500 more and the other quoted $8-900 more. How important is it? I'd hope with the liner that we only need to do it once in this house and I want to get it right. If we went ahead without the insulation, would the pour down stuff be a reasonable option when we have more $$?

 

[webby3650]

The pour in insulation isn't a good option for a fireplace insert. It would be best to wrap the liner with insulation before installing it.

We don't really give an option unless the liner just won't fit with insulation. It's just part of the price, because it makes a big difference on an exterior chimney, and is required if your clay flue liners are busted.

 

[Todd 2]

It gave me what I thought was an over draft but I have learned to adjust for it, now I like the stronger draft. After a month of solid burning now I checked for that hated black stuff an to my suprize none to be found, only a light (very light) coating of brown dust. Good wood and the insulated liner has seemed to do the trick against the battle of the black chimney curse.

Todd2

 

[chimneylinerjames]

Agreed 100%. The wrap is what is needed for an insert kit. Do it right. Always insulate a wood stove liner. Like webby3650 said, I always include the insulation in the price, never separate it on the estimate. It is what needs to be done, so I never showed the customer it was even an option. Do it right the first time.

 

[SteveT]

I'm looking to install a wood stove into my fireplace. The chimney is 8"x10" and 25-30 feet long.
All of the new stoves we are looking at take a 6" flue. None of the installers that I talked to mentioned insulating the liner. When asked, one quoted me $500 more and the other quoted $8-900 more. How important is it? I'd hope with the liner that we only need to do it once in this house and I want to get it right. If we went ahead without the insulation, would the pour down stuff be a reasonable option when we have more $$?

I think a lot of the answer depends upon where the chimney is located. In my case, Cape Cod style house, the chimney goes through the center of the house. The masonry on the upper level gets quite warm and makes a huge contribution to heating the upper level; if the chimney was insulated much of the heat would be lost to atmosphere. If the chimney is external, like on the end of the house, I'd have insulated it.

 

[sailor61]

Where is your chimney located? Also with flue tile that are 8 inches wide you may have a devil of a time getting a wrapped liner down 25 ft.

I would suggest modifying your poll to ask if they have an interior or exterior chimney. Mine is somewhere in between - it was exterior and a subsequent addition covers about 3/4 s of it.

I did not insulate the liner (tile is 7 1/2 by 11 and was told by Rockford not to waste my money since there was no way I would get the 6" liner in place with the 8 inch dimension) and am getting good draft. Did add roxul into the damper area but that was to deal with heat going up into the chimney - it has not changed the draft.

 

[Jack Fate]

I think a lot of the answer depends upon where the chimney is located. In my case, Cape Cod style house, the chimney goes through the center of the house. The masonry on the upper level gets quite warm and makes a huge contribution to heating the upper level; if the chimney was insulated much of the heat would be lost to atmosphere. If the chimney is external, like on the end of the house, I'd have insulated it.

Always wanted to ask this question . I to have same set up . I don't want to do a upgrade & regret it . Before you tell me it's about the stove draft , I know that but there are always trade offs.
Also know one thing there is only one way to figure it out & might tAke a few years of intel

Cheers

 

[EatenByLimestone]

Any chance you'd be up to putting the liner in yourself?

I used a bucket to make it easier to get to mine. It did the grunt work of lifting an almost 30 ft long insulated liner into the air and allowed me to twist and push it with leverage.

Matt

 

[woodybiomass]

I recently lined (w/o insulation) my 25 foot 2/3 interior, 1/3 exterior 18"x21" chase. After burning my Oslo for 4.5 winters in an unlined chimney, all I can say is WOW! My understanding is: if you want your appliance to perform efficiently (the way it was designed to), and, you have a 25'-30' run then you can get away w/o insulation. Keeping flue gases warm is probably better for your liner, but, she's still going to draft real nice with your chimney height. Have fun!!

 

[weatherguy]

Yeah, interior/exterior makes a difference, I couldnt fit an insulated liner down mine which is in the center of the house, if it was an exterior I would have done the pour down insulation.

 

[EatenByLimestone]

Don,t forget to look into 5.5" also. With the long flue they may be an option.

 

[begreen]

I have an 35 ft uninsulated 6 inch ss duravent liner installed in 8 inch double wall zero clearance prefab using a small noncat buck 18 insert. Liner and original chimney creaks and makes noises during expansion from heat. With blower off I can hear a low frequency rumble from the draft, even with primary air controls turned down. Would insulation help or would it even fit into the original flue with two 45 deg elbows?

I suspect that there are two 30º elbows in the original flue. 45º elbows are not made or allowed in high temp pipe. 6" Duraliner might work, it's preinsulated. Actually at 35' I would consider dropping down to 5" Duraliner.

 

[jankdc]

Thanks for the responses. I have an exterior wall chimney. What is wrong with the pour insulation? Also, I'm hearing that a 5.5 inch liner with insulation would be better than a 6 inch liner without. Ideally 6 inch with insulation though. BTW, I will be paying to have an installer put it in.

 

[woodybiomass]

Why do you not need insulation w/ over 25 ft run. Mine is center of house 2 story. Any feedback is much appreciated.

Because at that height you will have crossed the threshold to a properly functioning appliance (with liner). What happens beyond that in terms of insulation, I do not know, and may never know! My house is uninsulated, and it's 76 degrees in here, therefor I'm happy good luck all

 

[begreen]

Thanks for the responses. I have an exterior wall chimney. What is wrong with the pour insulation? Also, I'm hearing that a 5.5 inch liner with insulation would be better than a 6 inch liner without. Ideally 6 inch with insulation though. BTW, I will be paying to have an installer put it in.

For pour-in insulation to work right the liner needs to remain at least 1" from the chimney walls all the way down. The insulation needs to completely surround the liner for at least an inch. That is sometimes hard to achieve in some installations. I believe they make spacers to attach to the liner to help achieve the 1" gap, but I'm not sure how many installers use them. With a pre-insulated liner like Duraliner, it doesn't matter if the liner contacts the chimney.

 

[webby3650]

What is wrong with the pour insulation?

You also absolutely have to completely block the throat of the fireplace flue, otherwise all of the insulation comes pouring out of the bottom. It's very messy and will make it pretty much impossible to use as an open fireplace in the future.

 

[tickbitty]

My masonry chimney is shorter than yours but we went with the insulflex for ease of installation. The cost of the liner (mail order) was comparable to many uninsulated liners and I believe at the time the cost was a little less than a comparable liner with a wrap kit. This was a few years ago, the costs may have gone up some but anyway the pre-insulated flex might be worth a look in your case.

As far as the pour-in stuff, I don't know. Although I don't forsee selling my house anytime soon, I do try to think of what a future owner might want to do. I cut the damper out, but I know if anyone wanted to use the fireplace as a fireplace again, they could pull a liner and put on a top-sealing damper easily. If they had to get the pour-in stuff out, I assume it would be a bit more work or mess.

 

[imacheezhead]

My Chimney is masonry with an 8" glazed clay flue liner. The chimney is about 25' tall and goes up through heated areas unil it gets to the unheated attic and up through the roof to the outside. the I clean it every fall before heating season. What I find strange is that any creosote build-up I get is at a point right where the pipe enters the chimney (about 6' above the base) and then up about 4 - 5' from there. You can see the chimney in my profile picture. Where the chimney goes through the cold attic and to the outside, it's always clean as a whistle. Go figure. I considered an insulated liner, but because of this wierd creosote pattern I figured it probably wouldn't do any good.

 

[denn]

A 7" liner will fit in a 16"X16" chim block.
Mix perlite with portland, 9 to 1 ratio, with air intraining agent (spelling)
Use just enough mortor between the liners to level them.
Don't morter your chim block to the liner at the top, cast a cap using wood as a mold.
When the liner heats up it will lift the top block up with the liner expanding if it's all
mortored together.

 

[begreen]

My Chimney is masonry with an 8" glazed clay flue liner. The chimney is about 25' tall and goes up through heated areas unil it gets to the unheated attic and up through the roof to the outside. the I clean it every fall before heating season. What I find strange is that any creosote build-up I get is at a point right where the pipe enters the chimney (about 6' above the base) and then up about 4 - 5' from there. You can see the chimney in my profile picture. Where the chimney goes through the cold attic and to the outside, it's always clean as a whistle. Go figure. I considered an insulated liner, but because of this wierd creosote pattern I figured it probably wouldn't do any good.

Are you still using that stack robber? Try a season of burning without it and see if there is a notable improvement.

 

[imacheezhead]

Are you still using that stack robber? Try a season of burning without it and see if there is a notable improvement.

I assume you are referring to the Magic Heat. Yes I am still using it and I don't see any appreciable difference in the amont of creosote buildup since I have been using it.

 

[Macpolski]

I am on the verge of pulling the trigger on a flexible chimney w/insulated liner. Been burning an Englander 13-nc for a bunch of years in a fireplace hearth with an outside chimney under 20'. The clay flue tiles are 13"x13". This year I am serious about getting a Woodstock Fireview so I don't want an insulated chimney liner installation redo/make-it-fit for the Fireview.

 

[homebrewz]

When I did mine, the insulation blanket for 30' of 6" flex liner was about $75 extra, purchased through the local sweep. They threw in a role of aluminum tape to secure the insulation.
Though, I did the install myself with a helper.

 

[HaTaX]

I have been wrestling which way to go with my chimney, and I think I'll end up going with the "probably over the top of what I need" setup from DuraVent. They have a nice oval system that will fit down my 8.5" x 13" clay tile liner with ease and the security of a rigid top half. The rigid stuff is pre-insulated and they make a nice easy wrap for the flexible portion, held in place with some clamps.

Not sure I need insulated, but this way my chimney would be code even if the existing tiles and masonry weren't up to snuff, so I ensure I'll have a good draft, and a very safe system in the event of a chimney fire.

Oval lets me keep the existing chimney completely intact with no modifications so it can be reverted easily, and it allows me to insulate the liner as well. After following this thread a little bit I decided that getting an insulated liner was worth it in the long run. And of note, at first this will be hooked to an OLD insert with a 8" outlet, the extra draft should help compensate for the loss of outlet size, there's just no way I'm dumping $1000 into a liner that won't accommodate 98% of the inserts sold today.