To insultate or not to insulate, expert advice needed...

[bbeals]

Got a little situation and I need some advice please. We had our Jotul 550 installed in mid September and have been burning around the clock anytime we have had weather that would allow for it, so we have probably been running it for 2-2.5 months. The insert is in a full masonry fireplace / chimney fully lined (24' SS) exterior chimney. two weeks ago I was traveling for work and the wife and kids started talking wood out of the wet stack and ended up burning (smoldering) about 30 splits or so of birch that I had just cut and split. Water came out of this stuff like wringing a sponge when I split it. I corrected the issue and covered the basics of only burning dry wood, but the damage had been done. The stove that drafted so well, now did not draft at all and would bellow smoke when you opened the door to stoke the fire. Anyway, I had quit burning for a couple of days until the sweep could show up (today). He took about a gallon of nasty creosote out of the stack and the cap was about 70% plugged with creosote (thus my draft issue). He agreed that the wet wood did not help matters, but recommended that we insulate the liner, as he believes that the exterior chimney coupled with it's size and height does not allow it to get and stay hot enough.

So back to the title, to insulate or not insulate, that is the question. Also, if we do insulate will this really make a huge difference in chimney maintenance? What would I expect to pay to have it insulated and what type of insulation is best for this? He suggest vermiculite?

 

[begreen]

It's definitely a good suggestion and will increase the flue temps. The stove will work better in mild weather too.

 

[webbie]

Well, first thing.....
If it runs 100% well most of the time when you are using it with dry wood, then we have to assume the problem had to do with operation and wood.

Also consider that the cap is above any insulated part, so with poor burning will probably clog anyway...even if insulated. The vast majority of the mess was probably at the cap and also in any elbo or right above the stove baffle (having fell down)...so keep that in mind - you may not need a sweep sometimes to clear out a blockage like that.

The only way to know whether insulation might make a big diff would be for you to burn it properly with seasoned wood for a couple of weeks and then inspect the chimney. If you don't have lots of goo and creosote, then you are probably OK.

To insulate, you have to either remove the liner and wrap it - or pour something down there. It should not be just vermiculite, because that stuff is too fine (like sand) and can run out of cracks in the chimney, etc.

There are mixes which contain cement and vermiculite, etc. which can be used for this process.

 

[oconnor]

In the end, insulate it for sure. How to insulate it depends on the liner manufacturer. Some allow vermiculite, others don't. I read one that doesn't allow anything around the liner at all (Selkirk I think, but don't recall). It all depends on how the had thier liner configured when it was UL tested.

As for other reasons to insulate - the Chimney Sweep Institue of America and National Fireplace Institue recommends it in thier best practices guidelines. See the link in my signature block.

As for cost - I was quoted around $500 for the ceramic wool wrap for my liner - plus install time.

Hope that helps.

 

[Hanko]

First suggestion is to educate wife and kids, by kicking wife and kids in ass. it clearly states in wood stove 101 not to burn wet wood. I have heard that the wool wrap stuff works good

 

[bbeals]

Well, first thing.....
If it runs 100% well most of the time when you are using it with dry wood, then we have to assume the problem had to do with operation and wood.

Also consider that the cap is above any insulated part, so with poor burning will probably clog anyway...even if insulated. The vast majority of the mess was probably at the cap and also in any elbo or right above the stove baffle (having fell down)...so keep that in mind - you may not need a sweep sometimes to clear out a blockage like that.

The only way to know whether insulation might make a big diff would be for you to burn it properly with seasoned wood for a couple of weeks and then inspect the chimney. If you don't have lots of goo and creosote, then you are probably OK.

To insulate, you have to either remove the liner and wrap it - or pour something down there. It should not be just vermiculite, because that stuff is too fine (like sand) and can run out of cracks in the chimney, etc.

There are mixes which contain cement and vermiculite, etc. which can be used for this process.

I like the suggestion. I will be burning much hotter than I had been due to the weather, early on we would shut the thing down for most of the day and only had it roaring in the morning and evenings. Draft has never been an issue and it was performing better than expected up until the wet splits found their way into the stove. As far as the cap is concerned, I believe this will be a continuous struggle. I looked at it and really don't like the design. The sweep also recommended a full SS cap for our chimney (has 3 flues). He said that a full cover would go over all 3 flues, allow for better exhaust, wont plug easily and will protect the chimney from water damage. All made sense to me, do you have experience with this type of chimney cap? I would also suspect that I could brush the chimney myself from the bottom up, as I will not brush it from top down (chimney cap is 40' off the ground and I have a 12/12 pitch on the roof.

 

[bbeals]

First suggestion is to educate wife and kids, by kicking wife and kids in ass. it clearly states in wood stove 101 not to burn wet wood. I have heard that the wool wrap stuff works good

I couldn't be too hard on them, they were quite proud of themselves keeping the fire going for a few days while I was gone. Just had to point out what stacks are at what stage and to only burn from the absolutely dry stack. I do not think the wrap would work for our setup. The flue is 7"x11" and the 6" SS liner barely made it down the flues. We will run it for a month with nothing but dry wood and always leave the air open at least an 1/8th. If the cap gunks, we'll put in a more open style, if the liner has a lot of creosote, then we will insulate.

 

[bbeals]

Our wood is dry, although I do not have a meter to give you specifics. It doesn't sizzle and takes right off, so is it safe to say that this was brought on by the wet wood that made its way into the stove, or could it also be from shutting the stove down at night? I always let the wood char for 15-30 minutes and then cut the air just before going to bed. It burns well in this configuration, I guess I am just paranoid now and not sure if I should be shutting it down that much.

 

[Hanko]

First suggestion is to educate wife and kids, by kicking wife and kids in ass. it clearly states in wood stove 101 not to burn wet wood. I have heard that the wool wrap stuff works good

I couldn't be too hard on them, they were quite proud of themselves keeping the fire going for a few days while I was gone. Just had to point out what stacks are at what stage and to only burn from the absolutely dry stack. I do not think the wrap would work for our setup. The flue is 7"x11" and the 6" SS liner barely made it down the flues. We will run it for a month with nothing but dry wood and always leave the air open at least an 1/8th. If the cap gunks, we'll put in a more open style, if the liner has a lot of creosote, then we will insulate.

I know what you mean, I actually went away for a weekend and the wife kept both stoves going. She thought she was hot stuff when i got home. Actually she did a good job, and didnt burn the house down

 

[dvellone]

depending on how much space there is around the liner you can save a lot of money by using a coarse grade vermiculite to insulate. Vermiculite comes in several grades from coarse to fine, so if you're concerned that the original clay liner (if there is one?) for some reason had some gaps in it you can use a heavier grade. Pulling the liner, wrapping, and resetting would be the thing I'd want to do after all else failed. Vermiculite is cheap in comparison and has all the insulating value you'll probably need. It is critical though that you seal the exit at the top of the chimney well to prevent any water from leaking into the insulation.

 

[DAKSY]

We use a product called "THERMIX" for insulating liners in deteriorated terra cotta flues...Cost about $40 per bag...
It has to be mixed with water before you pour it & you have to block off the damper area with a plate to keep everything from falling into the FP..
It kinda clumps up like cat litter & after it cures, it form a solid mass of insulate.
If you can find a dealer, they'll have the formulas for determining how many bags you'll need for specific diameter liners in particular flue tile sizes...
HTH

 

[bbeals]

We use a product called "THERMIX" for insulating liners in deteriorated terra cotta flues...Cost about $40 per bag...
It has to be mixed with water before you pour it & you have to block off the damper area with a plate to keep everything from falling into the FP..
It kinda clumps up like cat litter & after it cures, it form a solid mass of insulate.
If you can find a dealer, they'll have the formulas for determining how many bags you'll need for specific diameter liners in particular flue tile sizes...
HTH

I appreciate the insight. Given that this is a new house with full clay flue, I do not want to put anything down that solidifies, not that I am planning on pulling my stove, but it seems that this is better suited for a quick fix on a bad chimney.

 

[burntime]

I vote insulate. Even if internal chimney. My stove worked well without it, after insulating it I can choke the stove down more and get a hotter burn Isn't that the whole point? Good luck!

 

[Bubbavh]

.... He suggest vermiculite?[/quote]

vermiculite contains asbestos!! I would advise against it because of the obvious health concerns and if you ever sell your house you are going to have a problem! It will be very expensive to remove!

 

[bbeals]

.... He suggest vermiculite?

vermiculite contains asbestos!! I would advise against it because of the obvious health concerns and if you ever sell your house you are going to have a problem! It will be very expensive to remove![/quote]

Good catch. (broken link removed to http://www.epa.gov/asbestos/pubs/verm.html)

Any suitable substitutes? I cannot wrap the line due to lack of clearance between it and the flue.

 

[Danno77]

.... He suggest vermiculite?
vermiculite contains asbestos!! I would advise against it because of the obvious health concerns and if you ever sell your house you are going to have a problem! It will be very expensive to remove!

First, vermiculite doesn't have asbestos in it anymore. Second, even if it did, don't blow a gasket. Asbestos doesn't hurt you unless you are breathing it.

 

[Bubbavh]

.... He suggest vermiculite?
vermiculite contains asbestos!! I would advise against it because of the obvious health concerns and if you ever sell your house you are going to have a problem! It will be very expensive to remove!

First, vermiculite doesn't have asbestos in it anymore. Second, even if it did, don't blow a gasket. Asbestos doesn't hurt you unless you are breathing it.

Vermiculite does still contain asbestos but in lower levels. You are correct about it not being dangerous unless you are breathing it. His insert has a blower on it, right? Even with a good tight block off plate you are probably still going to be circulating air passed some of it. Yes I know it's low levels but asbestos at any level is some real bad stuff!! I would shy away if it were my house!
My grandfather had breathing problems from exposure to it not a pretty sight towards the end!

Just trying to give the OP a heads up!

 

[Danno77]

fair enough. everyone has to weigh the risks involved and make an informed decision. For me, what may be an insignificant risk, may seem like a substantial risk to another, as long as we have all the information it's up to us each to make a decision.

 

[dvellone]

" asbestos is not intrinsic to vermiculite and only a few ore bodies have been found to contain more than tiny trace amounts." This quote from the EPA.

You can readily research all the reliable info. on vermiculite to better make your decision if you're concerned about it.
Lots of fears still around, and rightly so, because of the asbestos content in vermiculite from certain mines years ago. This isn't so today.

People will breathe in asphalt fumes, paint fumes, silicone fumes, dust and gypsum particulates when sawing lumber or sheetrocking, fiberglass when insulating, silicates when mixing mortars and ingest preservatives without much concern but mention asbestos and they will fly into a panic.

You certainly don't want your house filled with asbestos particulates , but as with using, cutting, or handling any building materials you take the precautions to protect yourself and your family.

I've worked as a Stone Mason for years and know more old timers that developed emphysema or died of lung cancer related to never wearing a mask when mixing mortar or cutting bricks and blocks. Any fine particulates, toxic or inert, can lead to cancerous lung tumors in a long term exposure situation like the workplace.

I agree with you in not wanting to fill the flue tile with a cement based product. This is usually done in a situation where the flue tile and chimney is in really rough shape and there is no other recourse other than take-down and rebuild. If your chimney is in good shape leave it that way and don't permanently limit your options.

 

[trouba]

Apparently the asbestos was at one plant no longer operational. asbestos VERMICULITE

 

[mellow]

Just my 2cents, last year I tried using my liner uninsulated in my exterior chimney and had the same results you are having, back drafting and creosote buildup. This year with the liner fully insulated it runs like a champ and creosote levels are way down, and I have a smoke dragon.

 

[bbeals]

Just my 2cents, last year I tried using my liner uninsulated in my exterior chimney and had the same results you are having, back drafting and creosote buildup. This year with the liner fully insulated it runs like a champ and creosote levels are way down, and I have a smoke dragon.

I am leaning toward the block off plate, insulation and will probably put in a damper to boot. I was down at the stove shop today looking at the Jotul 500 for my basement and was fully impressed at how that unit can be shut down for a slow / hot burn. I get too much draft on the stack and cannot turn mine down that far. I figure that if I insulate, I should be able to throttle the damper back at night for a longer burn.

 

[jtp10181]

https://www.hearth.com/talk/threads/30019/

 

[jgoodnow]

Has anyone tried Perlite, either loose fill or mixed?

http://www.perlite.org
(broken link removed to http://www.perlite.org/perlite_info.htm)

Look for "chimney" on the perlite_info page.