# Wood stove insert installation advice; Do I need to insulate liner? Is a reducer a bad idea?



## a316co2000 (Feb 11, 2014)

Hi everyone,

I'm hoping someone can help clear up some conflicting information I've been finding in regard to whether or not I need to insulate a stainless steel chimney liner during installation of a wood stove fireplace insert, and if using a reducer/adapter to save on chimney liner expense is a bad idea or not.

I live in Springfield, VA (think DC area) and just purchased a 2-story home built in 1972.  The house has a normal fireplace (no insert of any sort) with a 13x13 chimney.  From my research, I believe it is an EXTERIOR chimney (it is located on an outside wall; if I go outside, I can see the brick chimney run the entire height of the house).

I recently came across an old Derco Grizzly insert (pictures of same stove from another thread attached), which I was able to pick up for free (and by free I mean it took 4 of us 2 hours to remove it from the fireplace it was in and hoist it into my truck).  The insert has a blower which I believe can be thermostatically controlled, as well as a catalyst combustor.  The outlet is on top and is round, 8 inches in diameter.  It was in pretty nice shape, but my wife doesn't like the "80s/90s" look of it, so I've sanded it and re-painted with a semi-gloss black high temperature paint.  It's actually turned out really nice looking thus far (still need to put it back together).

Now for my questions, of which I have two: 1) Do I need to insulate the stainless steel liner?  2) Is using an 8" to 6" reducer to save money on a liner a bad idea?

1) Unfortunately, the previous owners just had it shoved in their fireplace with no liner, so now I need to purchase one.  I've been doing a lot of searching online and in local fireplace supply stores, and I'm finding conflicting information as to whether or not I really NEED to insulate the liner.  Some websites (typically the ones trying to sell me something) say insulating is an absolute must; others say it's recommended; some say it's not necessary.  I went to a local store and the guy working there said when they do liner installs they don't insulate because we live in VA where we don't have sub-zero winters, and that if we were in Wisconsin, etc. it would be another story.  I don't know if this guy is a moron, or if he actually knows what he's talking about.

I'm in the military, so I know I'm only going to be in this house for 4 years (3 more winters after this one), so any savings on utilities from having a liner installed is only a concern for the time I'll be living there.  After that I would like to rent the house out, so my chimney maintenance expenses could continue indefinitely if I do so.  Not sure how that plays into decision-making on whether or not to insulate.

What I do know is that the cost to insulate an 8-inch, 25 foot liner is very high.  I've located a non-insulated liner kit on craigslist, still new in box, for $400, and I believe I can talk the guy lower.  However, insulating the liner will cost me another $300-$350 (that's the cheapest I'm able to find it online).  I've seen some pre-insulated kits, but they're all 6" liners.

Do I really need to insulate my liner?  Is the benefit worth the cost considering how long I'll live in the house?

2) I could save hundreds of dollars on a liner kit if I buy an 8" to 6" reducer like the one at this link: http://www.firesidechimneysupply.co...rce=googleps&gclid=CNGFj6ekxLwCFeJj7Aoda14Agw.  I've been advised (by people trying to sell me stuff) that using a reducer will cause draft problems and make the stove less efficient, but if that's the case, why do they even make them?

Is using a reducer really a bad idea, or is the chimney supply guy just trying to sell me a more expensive liner, and more expensive insulation?

Here is a thread that relates to my exact stove make/model.  I've found it useful and it may answer other questions specific to my stove: https://www.hearth.com/talk/threads/need-advice-on-derco-grizzly-stove.80317/.

I really appreciate any help/advice anyone can offer.


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## Jags (Feb 11, 2014)

In a perfect world...Insulated 8" liner.  Throw in an insulated blockoff plate above the stove.


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## a316co2000 (Feb 11, 2014)

Jags said:


> In a perfect world...Insulated 8" liner.  Throw in an insulated blockoff plate above the stove.



Let's say my world isn't perfect...financially speaking, and I'm trying to save a little cash while still being safe...


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## Jags (Feb 11, 2014)

If your chimney is solid - then a simple liner will be a safe install.  Reducing the size of the pipe is untested for that stove.  Will it be safe - probably.  Will it work correctly - no idea.  Are you willing to take the chance that the 6" won't draft properly?  What happens if it doesn't and you have to pull it and STILL go with the 8".

My personal opinion is that other than cost - there is no downside to insulating a liner.  For a one time fee of a couple hundred bucks I would try to figure out how to make that happen.

And don't forget the blockoff plate.


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## begreen (Feb 11, 2014)

Seems like it is drafting ok if you are currently dumping into a 13 x13" chimney with no issues. You might be ok with 6" insulated, but it is not advised. If you do put in 6" insulated it will be an experiment. Any liner you put in will be safer than the current setup. 

PS: I updated your poll.


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## mstoelton (Feb 11, 2014)

+1 on the blockoff plate.  Instructions on how to make it are found on this site.


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## RickBlaine (Feb 11, 2014)

How to make a metal block-off plate:  https://www.hearth.com/econtent/index.php/articles/making_a_block_off_plate/

...and thank you for your service!  My brother is USAF (a pilot) and he and the wife have a house in Old Town, Alexandria.  They have two fireplaces that they don't use because of the inefficiencies.  If my conversion goes well, then this summer we will convert those two.  Good luck!

(BTW, that was a very well-written post)


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## a316co2000 (Feb 11, 2014)

First, thanks everyone for all the advice and for replying so quickly.

I do have a few follow-up questions:

1) Jags, when you ask if my chimney is "solid," are you asking if it's in good shape?  I had it inspected a month ago when the wood stove insert was just a pipe dream, and the guys said there were some exterior cracks that would need repair ($300), but other than that they said it was in great shape...didn't even need to be cleaned.

2) Jags, what does the blockoff plate do?

3) begreen, I haven't used the stove yet, so I don't know how it would draft.  It's currently sitting in my garage with the paint drying, and I wasn't planning on installing it until I got the liner kit.  Thanks for updating my poll.

4) mstoelton, did you forget the link for how to make that blockoff plate?  EDIT: Nevermind, someone posted one.  Thanks RickBlaine, and good luck to you (and your brother) too.


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## Jags (Feb 11, 2014)

Yes, by "solid" I mean in proper working order.
A blockoff plate will keep the heat from going up the open chimney.  It will improve your heating performance.


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## KindredSpiritzz (Feb 11, 2014)

I understand  budget limitations all to well. If it was me i'd just do the uninsulated 8 inch liner and maybe have to clean the chimney more if you get creosote buildup.


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## a316co2000 (Feb 11, 2014)

KindredSpiritzz said:


> I understand  budget limitations all to well. If it was me i'd just do the uninsulated 8 inch liner and maybe have to clean the chimney more if you get creosote buildup.



If I do, is an annual cleaning recommended?  Again I live in VA so the stove would typically be used primarily from late November to mid-March, at most.


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## Jags (Feb 11, 2014)

a316co2000 said:


> If I do, is an annual cleaning recommended?



At a very minimum it needs to be inspected/swept once a year.  For newbys, I HIGHLY recommend a more frequent inspection/sweep until you know how things are going.

ETA - Get on the wood processing now.  You are already running short on time to get dry fuel for next season.


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## a316co2000 (Feb 11, 2014)

Jags said:


> At a very minimum it needs to be inspected/swept once a year.  For newbys, I HIGHLY recommend a more frequent inspection/sweep until you know how things are going.
> 
> ETA - Get on the wood processing now.  You are already running short on time to get dry fuel for next season.



Thanks, will do.  Would insulating reduce the frequency of inspections?

I've already started working on wood.  Fortunately for me there are lots of "free firewood" posts on the local craigslist, and I have access to a log splitter.


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## Jags (Feb 11, 2014)

a316co2000 said:


> Thanks, will do. Would insulating reduce the frequency of inspections?


It _can_.  An uninsulated flue will typically run cooler wall temps.  They loose heat to the surrounding brick/stone/clay liner.  Insulating helps retain the heat in the liner which in turn keeps the temps in a safe operating range and can improve the draft.  All good things in respect to creosote production.


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## KindredSpiritzz (Feb 11, 2014)

insulating might reduce the frequency of cleanings, i'd still do it at least annually.  Mine burns dirty so i clean once a month thru the season, your need may vary from  mine.


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## BrotherBart (Feb 11, 2014)

$400 for the liner kit is great. I live South of Manassas and have a 21' un-insulated liner in my outside brick chimney. Since it is a double flue chimney it should be about as bad a heat sink as you can find but the liner works great. It has a block off plate at the bottom with Roxul insulation on top of the plate and a little Roxul packed under the chimney liner top plate.

I have been burning since late October and went up to take a look this morning before the snow storm hits. Not gonna need to brush it till the end of the season. But you need to figure on at least an annual chimney cleaning. You change the oil in the car. You get the central heating unit serviced. Clean the chimney.

People talk about how outside chimneys are so inefficient but I slipped my infrared thermometer in my pocket before I hit the ladder today. I had to go check it with the stove burning due to time constraints. The stove was burning at a steady 540 degrees stove top and the very top of the liner was at 328 degrees. It was 18 last night and 22 while I was up there. Bad boy ain't loosing squat to those bricks around it.

Get that eight inch liner and install it, load and go. But you are gonna need good dry, seasoned ain't a word, wood, examine that cat and find out the proper way to operate that cat stove.

Welcome to hearth.com neighbor.


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## oconnor (Feb 11, 2014)

I feel the pain of the four year house, bought four in my time flying for the Queen here in Canada. Usually get it just the way I like it, then it's time to sell.  

If you can, insulated it to keep it warmer and reduce creosote. If you can't, then install it with a full liner and block of plate.  Bart is right, if you burn it right with dry wood your setup should be fine. Enjoy.


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## bholler (Feb 11, 2014)

The insulation doesn't cost that much and it will improve performance and safety of your system.  Also almost all liner manufacturers require it and will void the warranty if you don't insulate.   As far as using 6" it might work but if it doesn't you will have wasted the time and money on that 6".


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## a316co2000 (Feb 11, 2014)

BrotherBart said:


> $400 for the liner kit is great. I live South of Manassas and have a 21' un-insulated liner in my outside brick chimney. Since it is a double flue chimney it should be about as bad a heat sink as you can find but the liner works great. It has a block off plate at the bottom with Roxul insulation on top of the plate and a little Roxul packed under the chimney liner top plate.
> 
> I have been burning since late October and went up to take a look this morning before the snow storm hits. Not gonna need to brush it till the end of the season. But you need to figure on at least an annual chimney cleaning. You change the oil in the car. You get the central heating unit serviced. Clean the chimney.
> 
> ...



Thanks neighbor.  I called the guy about the $400 craigslist liner kit.  His has a "tee connection" which would be useless to me, but it doesn't have the appliance/stove connector that I would need to connect it to the top of my stove insert.  He said he would take $350 for it, but I'd likely have to spend $50 on the missing appliance/stove connector, so I'm still looking at $400.

I found this liner kit on ebay: http://www.ebay.com/itm/8-x25-316TI...394?pt=LH_DefaultDomain_0&hash=item3cc86182a2.  $435 plus free shipping for the complete kit sounds like a better deal than $400 total with the hassle of driving to the guy on craigslist and back, plus buying the appliance/stove connector separately, so I think I'll be ordering from ebay.

I called the seller on ebay with some clarification questions and he was pretty much a used car salesman, which was annoying.  Aside from trying to tell me their prices were more than what ebay listed, he did have some useful info.  He said that if I wasn't going to insulate the entire liner I should put "insulation plugs" at the bottom and top of the liner, which I'm assuming is the same as what you did with the Roxul insulation on top of the block off plate and under the chimney liner top plate.  Is applying this insulation in those two places as simple as it sounds?  He tried to sell me two of these to get the job done: http://www.chimneylinerdepot.com/store/903/product/No-Foil-High-Temp-Insulation-Section-24x48.html; but I'm pretty sure the Roxul is a more cost effective alternative.  Is this the stuff I would need to get?http://www.lowes.com/pd_138683-1278...t=roxul&pl=1&currentURL=?Ntt=roxul&facetInfo=

Thanks for all the advice everyone.  I'm really learning as I go here.


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## bholler (Feb 11, 2014)

One big factor for weather or not to insulate is can you confirm that you have proper clearances to combustibles on the entire chimney?   if not you should insulate because by insulating you get a zero clearance to combustibles on the exterior of the chimney


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## BrotherBart (Feb 11, 2014)

Springhill on eBay is Chimney Liner Depot. Good bunch to do business with. I have myself.


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## BrotherBart (Feb 11, 2014)

Yeah that is how I did it and what I did it with.


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## BrotherBart (Feb 11, 2014)

bholler said:


> One big factor for weather or not to insulate is can you confirm that you have proper clearances to combustibles on the entire chimney?   if not you should insulate because by insulating you get a zero clearance to combustibles on the exterior of the chimney



13 X 13 tiles and an eight inch liner gives you the clearance to combusibles before you even get to the the tiles. Much less the bricks or the framing members.


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## bholler (Feb 11, 2014)

Were did you get that info bart?   Clearance to combustibles on a bare pipe is 18" minus 1/3 for the masonry is 12" right.  you will have an 8" pipe centered in a 11" flue that is 1.5" not 12".  Ok I saw he said 13 by 13 even if that was the inside size that would still only be 2.5"


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## bholler (Feb 11, 2014)

http://www.rockfordchimneysupply.co...nd-Maintenance-Instructions-for-Rock-Flex.pdf
http://www.nationalchimneysupply.com/wp-content/uploads/2012/05/CB-installation-instructions.pdf
http://lib.store.yahoo.net/lib/elitedeals/ventinoxduraflexproandswinstructionmanual.pdf
here are a few sets of installation instruction I found all say that to meet ul-1777 specs for zero clearance to combustibles in a masonry chimney insulation is required.


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## BrotherBart (Feb 11, 2014)

Rockford:

For Solid Fuel Applications
Insulation provided for the Rock-FlexTM system will be a single ½” (13mm) thick layer of insulating blanket. This insulating system
is listed to allow zero clearance from the chimney masonry exterior to combustibles. The 8 lb. density insulating blanket must be
wrapped around the entire length of the liner in an* unlined, partially lined, or cracked clay tile liner application*.


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## bholler (Feb 11, 2014)

still not seeing the source for your info that you get to zero clearance by the time you reach the tile.


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## BrotherBart (Feb 11, 2014)

If you have a suggestion to make in response to the OP's questions, make it. If you want to discuss liner installation issues, start a thread.


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## bholler (Feb 11, 2014)

ok that one is not clear as to clearances for a clay lined chimney look at nationals it is very clear it states that "if the proper clearances listed above cannot be determined the liner must be installed with a ul listed chimney insulation"  I wish I could find the installation manual for the liner he is looking at but I couldn't find it.


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## bholler (Feb 11, 2014)

I am telling the op that he should insulate the liner which I believe was his original question.  And he is right there is allot of conflicting info but if you read the instructions ratings or industry hand books it is pretty clear.


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## a316co2000 (Feb 11, 2014)

bholler said:


> I am telling the op that he should insulate the liner which I believe was his original question.



I'm a little confused...

My chimney, as far as I can tell, is brick and mortar.  Is that the same as "clay lined?"

What does zero clearance mean?


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## bholler (Feb 11, 2014)

I am sorry a316co2000 I assumed because your sweep said it was good to go it had a good clay liner in it.  Do you know if it does or if it is unlined brick? And zero clearance means that combustible materials can be touching the outside of the masonry structure.  Required clearances from the exterior of a masonry chimney is 1" for an exterior chimney and 2" for an internal one.


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## a316co2000 (Feb 11, 2014)

BrotherBart said:


> Yeah that is how I did it and what I did it with.



I'm assuming there's a reason doing what I'm about to propose would be a bad idea, but if so, it's not obvious to me why.  That said...

The rolux comes in packages of 59 square feet of insulation for $37.  If 59 square feet is enough insulation to do so, would it be beneficial to wrap the rolux around the liner and secure with something like this: http://www.amazon.com/3M-High-Tempe...TF8&qid=1392163446&sr=8-1&keywords=flue+tape; or this: http://www.amazon.com/CS-Hyde-Tempe...163506&sr=8-2&keywords=high+temperature+tape?

I know the rolux can handle the temperature, and it seems like insulating the liner in this manner would be better than not insulating it at all.


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## BrotherBart (Feb 11, 2014)

Brick and mortar is the outside of the chimney structure. If the place you made the 13X13 measurement was orange ceramic material that is the interior flue tiles. Which I have no doubt are there are that sweep would have never blessed your chimney. And in 1972 virtually all building codes required flue tile lining in chimneys.


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## bholler (Feb 11, 2014)

yes bart which is what I assumed also but that is not necessarily true I just wanted to check.


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## a316co2000 (Feb 11, 2014)

bholler said:


> I am sorry a316co2000 I assumed because your sweep said it was good to go it had a good clay liner in it.  Do you know if it does or if it is unlined brick? And zero clearance means that combustible materials can be touching the outside of the masonry structure.  Required clearances from the exterior of a masonry chimney is 1" for an exterior chimney and 2" for an internal one.



I have no idea if it is clay or if it's unlined brick.  The house was built in 1972 and I just bought it in June of last year.  I tried opening the damper and shining a flashlight up it, but I really couldn't tell what I was looking at.


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## BrotherBart (Feb 11, 2014)

It can be done but the hassle ain't worth the couple of hundred bucks or so a real insulation kit will cost you.


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## a316co2000 (Feb 11, 2014)

BrotherBart said:


> Brick and mortar is the outside of the chimney structure. If the place you made the 13X13 measurement was orange ceramic material that is the interior flue tiles. Which I have no doubt are there are that sweep would have never blessed your chimney. And in 1972 virtually all building codes required flue tile lining in chimneys.



I didn't take the 13x13 measurement, I just read it off of the inspection paperwork.  I looked on the paperwork and I don't see any info about clay or tile lining.


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## BrotherBart (Feb 11, 2014)

Where did you get that 13X13 measurement?

We were typing at the same time.


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## BrotherBart (Feb 11, 2014)

a316co2000 said:


> I didn't take the 13x13 measurement, I just read it off of the inspection paperwork.  I looked on the paperwork and I don't see any info about clay or tile lining.



So we are back at square one. No clue what chimney you have there.


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## a316co2000 (Feb 11, 2014)

BrotherBart said:


> So we are back at square one. No clue what chimney you have there.



What type of chimney/liner would require me to insulate the liner, and what type(s) would not require me to?


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## bholler (Feb 11, 2014)

If it in fact is unlined I believe every one would agree to insulate it  13 by 13 is not a standard clay liner size so it might not be lined but I guess no point in speculation.  And I am sorry if I offended you bart not my intention I know you know your stuff I just disagree with you on this point.


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## a316co2000 (Feb 11, 2014)

bholler said:


> If it in fact is unlined I believe every one would agree to insulate it  13 by 13 is not a standard clay liner size so it might not be lined but I guess no point in speculation.  And I am sorry if I offended you bart not my intention I know you know your stuff I just disagree with you on this point.



If it is not lined, wouldn't the chimney inspector have mentioned that?

EDIT: I just looked at my home inspection report from when I bought the house and it says "Flue: lined"  It doesn't say how it is lined.


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## BrotherBart (Feb 11, 2014)

It can only be speculated what you have there. But a 12X12 interior diameter flue tile is 13X13 exterior diameter. But somebody needs to get a look at that thing to know for sure what you need for it. Frankly, at his point I wouldn't advise you doing this DIY.


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## a316co2000 (Feb 11, 2014)

BrotherBart said:


> It can only be speculated what you have there. But a 12X12 interior diameter flue tile is 13X13 exterior diameter. But somebody needs to get a look at that thing to know for sure what you need for it. Frankly, at his point I wouldn't advise you doing this DIY.



I'm going to call the company that inspected the chimney tomorrow and see if they have a record of how it is lined.


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## BrotherBart (Feb 11, 2014)

If you are thinking about lining this thing yourself sooner rather than later you are going to have to go up there and take a look down that thing and see what you are getting into. Taking a camera and tape measure with you should be a part of that trip.

Not the next three or four days of course. Ten inches of snow on the roof is gonna be a bummer.


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## a316co2000 (Feb 11, 2014)

BrotherBart said:


> If you are thinking about lining this thing yourself sooner rather than later you are going to have to go up there and take a look down that thing and see what you are getting into. Taking a camera and tape measure with you should be a part of that trip.
> 
> Not the next three or four days of course. Ten inches of snow on the roof is gonna be a bummer.



I planned on going up there and dropping a tape measure down before buying the liner to ensure I get one that's long enough, but I was hoping to get a 40 degree day before doing so.  I would prefer to make it a DIY project.  The chimney inspection company quoted me $1,500 when they came to do the inspection, the cheapest by far of anywhere else I called for an over-the-phone quote.  As good a deal as that is relative to other companies, $1,500 isn't exactly in the budget right now.  The Air Force pays me well, but they don't pay me THAT well.

Would any speculation on what type of chimney I have be irrelevant if I just went ahead and insulated the liner?  I'm not throwing in the towel on avoiding the insulation cost, but worst case scenario, would that make me safe no matter what?


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## Big Dan (Feb 11, 2014)

nobody said what the bare minimum to do to get it to pass inspection is it might just be a flu connector that's cheap. but I wouldn't recommend just putting in a flu connector


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## BrotherBart (Feb 11, 2014)

No way to know until we know what that chimney is. Lining a chimney isn't a walk in the park. It is a dirty, dangerous job with the working on a roof factor. And you virtually always have some kinds of obstructions and offsets in the chimney.


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## BrotherBart (Feb 11, 2014)

Big Dan said:


> nobody said what the bare minimum to do to get it to pass inspection is it might just be a flu connector that's cheap. but I wouldn't recommend just putting in a flu connector



You are talking about a direct connect, and that is out of the question.


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## oconnor (Feb 11, 2014)

I just reread the first post and noticed your plan to rent the house after your next posting. If I was planning on letting a tenant use the stove, I'd want the insulated liner. Safer if a chimney fire happens, less likely to creosote up, etc, etc.


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## a316co2000 (Feb 14, 2014)

BrotherBart said:


> No way to know until we know what that chimney is. Lining a chimney isn't a walk in the park. It is a dirty, dangerous job with the working on a roof factor. And you virtually always have some kinds of obstructions and offsets in the chimney.



I called A+ Chimney Cleaners (the company who inspected my chimney), and they were able to tell me that I had a standard clay chimney.  Despite my pride hurting, as well as my wallet, I think I'm going to pay them to do the work.

The best price I was able to find for the 8" x 25' liner kit and insulation was $660.  A+ said they were a little low on business right now so they would do the install, with parts, for $1,250.  If I was going to live here forever, or if adding a wood stove insert to the house added any resale value, paying the $600 difference for someone else to do the dirty work would be a no-brainer, but since I'm going to be heading wherever the Air Force sends me in the summer of 2017, shelling out the extra cash does hurt a bit.  I'm not sure if I'll be able to recoup the expense in energy savings over the next 3 winters, and my friend is still convinced we're capable of doing the work ourselves, but the cautious side of me (a very small part of my inner being) says to pay the contractor.  My concerns of doing the work myself are:

1) Accessing the top of the chimney.  I've been on top of my roof, but the chimney sticks up another 8 feet.  I don't exactly have easy access to scaffolding, so I'm not really sure how I would safely get up there to install the top plate.  I couldn't exactly stand on the roof like this guy: (see picture)

2) Obstructions in the chimney.  It seems like a 13x13 chimney is plenty of space to shove down an approximately 8.5 inch diameter tube, but I have no idea how I would deal with having to remove obstructions inside the chimney, should they exist.

Thanks everyone for the advice and expertise, and please feel free to offer more if you have it.  This was my first hearth.com experience and I was very impressed with the plethora of knowledge and willingness to share.  I had no idea forums could be so useful.

Damn it...even as I sit here typing this I'm thinking "what if we could just do it ourselves?"  Probably always going to wonder that...


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## BrotherBart (Feb 14, 2014)

Good decision. I have done them but for six hundred I would let somebody else do the next one. Everything doesn't have to do with pride or return on investment.


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## Dave A. (Feb 14, 2014)

a316co2000 said:


> t seems like a 13x13 chimney is plenty of space to shove down an approximately 8.5 inch diameter tube,



It's not 13x13 inside.  It's only 11x11 and the liner with 1" insulation will be around 10.5".  It may be tight. (Unless I'm misunderstanding and it's actually a 16x16 clay liner which is 13.5x13.5 inside.)

There also are preinsulated liners.  Insulflex comes to mind.   You mentioned "like used car dealers".  That's probably the right idea as far as pricing goes.  Have gotten the impression that you can bargain on the price for these liners a lot of the time like with a car.  It's not like buying from a dept. store.


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## woodgeek (Feb 15, 2014)

I still think an 8" liner is a bit of a white elephant....most new EPA inserts require a 6".  I say go for an insulated 6" with a blockoff, save a little money, and use the current freebie insert.  If it doesn't burn right...sell it on CL for more than you paid for it (free) and use the cash to buy something else on CL.  IM(Humble)O an insulated 6" liner is gonna pull a lot better than a slammer in an exterior chimney, unless its 12' tall.  Oh yeah, how tall is the stack?


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## bholler (Feb 15, 2014)

Yes wood geek it may work but my thought is it will not pull as well as it should causing more buildup.  and as soon as you start to get build up in that 6" you are going to have lots of problems.


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## woodgeek (Feb 15, 2014)

Comes down to the operator.  A bad operator could choke up an 8" liner, a good operator could keep a 6" liner clean, esp with a cat.  Might just be a slight air adjustment difference between the two cases, same airflow and burn profile otherwise.

Unless you were planning on getting 1" of creosote in the liner, I don't see what the liner size would have to do with it.

Alternative scenario is OP squeezes in $$$ 8" liner, and then decides the old insert is no good (just as likely IMO as having a problem with a 6" liner), and now he is locked into finding a new unit that takes an 8" liner, pretty much blocking him from anything of a newer vintage.


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## bholler (Feb 15, 2014)

while I agree with you wood geek that it will come down to the operator.  It will be much harder for someone to operate the stove properly with a liner that is only 3/4 the necessary size.  Also if he is thinking of renting the property everything needs to be done to code and to make it as easy as possible for someone to operate.   That means insulating and no down sizing.


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## woodgeek (Feb 15, 2014)

How times change....

this thread from 2007 describes a Derco cat stove as a pre-EPA unit that is best suited to being a 'boat anchor'.

https://www.hearth.com/talk/threads/modified-need-advice.11157/

In 2014 we have 3 pages of discussion on the importance of spending $1000 for an *8" insulated liner*.  LOL.

I'm no snob....I'm running a 35 yo pre-EPA insert with a 8" direct connect.  But I wouldn't burn it 24/7, or plan on letting renters do it! 

I still say the OP can scrap the DERCO, put in a $600 6" liner and put the $400 left over towards an EPA unit.


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## bholler (Feb 15, 2014)

I agree with you on that point for sure wood geek.  But that was not his question I answered his question as best I could.  But if it were me I would get a better stove and put in a 6" insulated liner as you suggested.


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## bholler (Feb 15, 2014)

I am no snob either I am running a almost 40 y/o cawley lemay 600.  But I would have to say it is a better stove than many of the newer ones out there.  It has secondary combustion burns clean and cranks out the heat.  But I do feel that a properly sized and insulated liner makes a stove much easier and safer to operate.


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## woodgeek (Feb 15, 2014)

further research reveals 3 cat models from DERCO are EPA listed:

                                                                                           g/hr   BTU/hr     % Eff
x Derco, Inc./Grizzly Stoves Super Achiever FPI-2-LEX   2.4  9800-34200  72   Catalytic
x Derco, Inc./Grizzly Stoves Little Blazer       FP-20          4.7  7200-28400  72   Catalytic
x Derco, Inc./Grizzly Stoves Little Blazer       FP-20          4.7  7200-28400  72   Catalytic

Free EPA stove in good condition....score.  Free pre-EPA requiring expensive venting....not a score.


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## Dave A. (Feb 15, 2014)

Don't recall an indication of s.ft. but if it's a larger house, being locked in with an 8" liner is not really a detriment in the current market for stoves.  All the larger than 3 cf ones require an 8" liner -- thinking  BK King, Buck  91, 94, Kuma Sequoia, et. al.  Besides he said it's a two story house, so the chimney is likely over 20' or more and with an 8" insulated liner, he should be able to use most stoves with 6" stove collars and an enlarger fitting, I would think if he decides to downsize.

I wouldn't look at the 8" insulated liner as a white elephant limiting his future options. In fact when I was planning to replace the too-small-for-me Century insert, I was disappointed that I only had a 6" liner which ruled out those larger stoves that required the 8".


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## a316co2000 (Mar 7, 2014)

Wow, lots of replies to this thread, yet stopped getting e-mail notifications and wasn't aware others had posted.  I wish I had seen these comments before making a decision, alas I did not.

I was able to negotiate multiple ebay sellers down to a total of $625 for an 8" 25 foot liner kit, and an insulation kit to go around it.  I also got up on the roof with a friend last weekend to ensure a 25 foot liner would be long enough, and to see if there were any obstructions.  It looked clear all the way to the bottom so we decided to do the job ourselves, which is when I ordered the parts.  They arrived 2 days ago, so I'm hoping to install the liner this weekend (depends on my friend's availability).

As for the stove, I still have hopes that it will perform to my satisfaction.  I found another forum on here posted by an owner of the exact same stove, and he was very happy with its performance, so hopefully I will be too.

The only challenge I foresee now will be getting past the damper.  The narrow part of it is only 6.5 inches, so I don't know if I should try cutting it or ovalizing the liner.  I'll post a separate topic on that discussion.

Thanks again everyone for the inputs and advice.


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## a316co2000 (Mar 7, 2014)

Found the thread I mentioned from another owner with the exact stove...here it is: https://www.hearth.com/talk/threads/grizzly-stove-why-did-the-go-out-of-business.116306/

Woodgeek, you asked how tall the stack was.  Could you clarify?  I don't know what that means.


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## woodgeek (Mar 7, 2014)

How much vertical from top of stove to top of liner.....sounds like 20-25'


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## a316co2000 (Mar 7, 2014)

woodgeek said:


> How much vertical from top of stove to top of liner.....sounds like 20-25'



Yes, it's a little over 24 feet


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## a316co2000 (Mar 11, 2014)

Well the job is done and the stove works great, though the weather has warmed up so we only really used it to make sure it worked (so far).

We ended up ovalizing the last 2 feet of the liner and, once getting it through the damper hole, made the end round again to connect it to the stove.  I decided to go with that method because after removing the damper (flapper part) it became evident I would have to remove some fire brick to avoid ovalizing the end of the liner, and I wasn't comfortable attempting that.  Ovalizing it did make it a little tougher to get it shoved down the flue, but with a little brute force we made it work, and I feel good about being able to do the job ourselves.

Thanks everyone for your advice, which ultimately led to me spending an extra $250 (though it is nice knowing the job got done right).  I'll post some pictures once I get the rest of the trim painted and put on the stove.


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## _CY_ (Mar 11, 2014)

a316co2000 said:


> Well the job is done and the stove works great, though the weather has warmed up so we only really used it to make sure it worked (so far).
> 
> We ended up ovalizing the last 2 feet of the liner and, once getting it through the damper hole, made the end round again to connect it to the stove.  I decided to go with that method because after removing the damper (flapper part) it became evident I would have to remove some fire brick to avoid ovalizing the end of the liner, and I wasn't comfortable attempting that.  Ovalizing it did make it a little tougher to get it shoved down the flue, but with a little brute force we made it work, and I feel good about being able to do the job ourselves.
> 
> Thanks everyone for your advice, which ultimately led to me spending an extra $250 (though it is nice knowing the job got done right).  I'll post some pictures once I get the rest of the trim painted and put on the stove.



good job on installing liner yourself .. now you've got two more issues coming .. making a block off plate and determining if Cat is still good.
a little late now for a tip to save $$$ on liner insulation .. then if you are having trouble with heat loss up chimney .. you can insulate entire firebox and damper area instead of a block off plate.  https://www.hearth.com/talk/threads...neral-wool-instead-of-block-off-plate.124737/

you can purchase high temp mineral wool rated to 2000f to insulate entire firebox, damper for about $40 for one bale of mineral wood insulation. which also comes in 1in thickness in long rolls to wrap liner .. enough to do entire liner for about $40-$80.

there's an incredible markup $$$ for online liner/insulation prices vs buying local .. provided you are in a large enough metro to have large building supplier and fireplace warehouse. rigid double wall 8in stainless about .020 in thick was about $10ft for 4ft sections.. higher for elbows and shorter pieces.


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## a316co2000 (Mar 11, 2014)

_CY_ said:


> good job on installing liner yourself .. now you've got two more issues coming .. making a block off plate and determining if Cat is still good.
> a little late now for a tip to save $$$ on liner insulation .. then if you are having trouble with heat loss up chimney .. you can insulate entire firebox and damper area instead of a block off plate.  https://www.hearth.com/talk/threads...neral-wool-instead-of-block-off-plate.124737/
> 
> you can purchase high temp mineral wool rated to 2000f to insulate entire firebox, damper for about $40 for one bale of mineral wood insulation. which also comes in 1in thickness in long rolls to wrap liner .. enough to do entire liner for about $40-$80.
> ...



I'm a little confused...are you saying I could have insulated the liner for $40-$80?  If so, that hurts.

As for online purchases, anywhere I could find that wasn't an online purchase was way more expensive for the liner.


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## bholler (Mar 11, 2014)

I don't think rigid double wall is a very good solution for an insert it would be next to impossible to get it hooked up right in the offset in the smoke chamber.  And the insulation you are talking about is tat a ul listed chimney insulation?  If not I don't think it is worth the money savings because you will not meet code and could void the liner warrantee.  I am sure it would work but I think it is worth buying he right stuff.


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## _CY_ (Mar 11, 2014)

a316co2000 said:


> I'm a little confused...are you saying I could have insulated the liner for $40-$80?  If so, that hurts.
> 
> As for online purchases, anywhere I could find that wasn't an online purchase was way more expensive for the liner.



yes .. mineral wool rated to 2000f is material used for liner insulation. follow link in above post for rest of details.


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## bholler (Mar 11, 2014)

I have seen that thread yes but I don't see that it is ul listed.  Like I said I am sure it is fine but if it isn't ul listed there is a very good possibility it will void the warrantee.  As well as not technically meet code which if you had a prick of an inspector he could fail you for it.  I am not saying you cant use it I am sure it is fine I am just saying I would not use it unless it is tested for that application.  All of the install directions I have seen call for a ul listed chimney insulation to be used if you need to insulate.


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## _CY_ (Mar 11, 2014)

bholler said:


> I don't think rigid double wall is a very good solution for an insert it would be next to impossible to get it hooked up right in the offset in the smoke chamber.  And the insulation you are talking about is tat a ul listed chimney insulation?  If not I don't think it is worth the money savings because you will not meet code and could void the liner warrantee.  I am sure it would work but I think it is worth buying he right stuff.



you are right that rigid liner is harder to install. one almost has to purchase extra pieces of different lengths to solve final connection puzzle.
final result is better due to thicker .020 stainless used all joints without locking tabs are screwed down.

IMHO a rigid liner is superior to a thinner flex liner. but is harder to install. believe it or not .. costs was much less due to buying all materials local. 16ft of double wall 8in stainless rigid including elbows and short sections costs right at $220 with tax. two bales of mineral wool 2000f insulation costs $90 with tax.

mineral wool used is rated to 2000f which the exact specification used for liner insulation.

it's made in all sorts of configurations from long 1in thick rolls to 2in x 24in x 48in and 4in x 24in x 48in , etc.
what I used had no backing .. much easier to wrap around liner and stuff upward 2-3 ft upwards past damper.

650C rated 8in stainless liner uses 2in of 2000f rated insulation inside a 12in diameter outer liner.
what I've done way exceeds 650C temp ratings .. inside an rock/mortar chimney that's several feet thick.


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## bholler (Mar 11, 2014)

I have no doubt that it is safe and probably exceeds insulation requirements but with out a ul label an inspector could fail it.  I agree about rigid being slightly more durable but we use heavy flex which is made from .015" metal I don't think that using rigid is worth the extra trouble for the slight advantage in thickness.


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## bholler (Mar 11, 2014)

I am by no means saying you are wrong on either count I just don't see that it is worth fighting with rigid and as a pro I feel I need to use tested and approved products and I will always recommend that to others


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## _CY_ (Mar 11, 2014)

bholler said:


> I have no doubt that it is safe and probably exceeds insulation requirements but with out a ul label an inspector could fail it.  I agree about rigid being slightly more durable but we use heavy flex which is made from .015" metal I don't think that using rigid is worth the extra trouble for the slight advantage in thickness.



looking from a professional's point of view .. time is money .. I'd go for the easiest to install without short cutting quality.
which is heavy stainless flex ..

but for someone doing the job themselves.  if it costs substantially less $$$ and delivers a safer installation ..
but takes 2x longer to install ... the lowest cost while delivering safest/best installation wins. 
going with heavy stainless flex would have more than doubled my costs.

installing the rigid really didn't take much more time .. what took the most time was cutting out damper large enough to allow an 8in liner through with 2in of insulation. more planning was definitely needed to figure out exact pieces needed and where insert collar would meet.


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## bholler (Mar 11, 2014)

I agree with most of what you said completely accept that rigid is safer than heavy flex I don't think there is any difference in safety between the two. I do see a potential problem with the rigid in that due to the difficulty in hooking up the joints in the offsets it is very possible that you may not get them completely together which could be a safety issue further down the road. Also what brand of insulated chimney did you get 16' of for $220 that is one hell of a deal


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## _CY_ (Mar 11, 2014)

bholler said:


> I agree with most of what you said completely accept that rigid is safer than heavy flex I don't think there is any difference in safety between the two. I do see a potential problem with the rigid in that due to the difficulty in hooking up the joints in the offsets it is very possible that you may not get them completely together which could be a safety issue further down the road. Also what brand of insulated chimney did you get 16' of for $220 that is one hell of a deal



didn't mean to imply rigid was safer than heavy flex .. they are equally safe .. the safest claim was from doing an install using 2000f rated mineral wool insulation way in excess of 650C ratings. Class A liner rating no where comes close.

yes one needs to be competent enough to snap liners together solid and screw down everything else. it's solid! NO way it's coming loose.
final joints are sealed with 2000f gasket cement, then covered with 1 inch hi temp rope held in place with a custom stainless 2in band. then covered with 2in 2000f insulation .. followed by filling in all voids with 2000f insulation.

concrete blocks were placed behind insert to prevent 650lb Buck 91 from moving.
anyone that knows their stuff can quickly tell this install was done right!


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## bholler (Mar 11, 2014)

sounds like a great install I just wouldn't ever want to do it.   lol


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## a316co2000 (Mar 12, 2014)

From what you're saying it doesn't sound like the savings are all that significant for the liner.  I ended up paying $385 for a 25' liner, appliance connector, and rain cap, with no tax and free shipping.  Granted, I had to negotiate a little over e-mail with the ebay seller, but given how much longer my liner was and the inclusion of the rest of the kit I think I did well, and without the hassle of piecing together multiple lengths of rigid liner.

Where your advice could have definitely saved me money would have been in the insulation, but if that's 2 inches thick it wouldn't have worked well for me anyway.  My flue was 11" x 11" and it was hard enough to cram the liner down it as it was.  Adding insulation that thick would have made it practically impossible.

On that note, I may buy some roxul and line my firebox with it.


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## _CY_ (Mar 12, 2014)

a316co2000 said:


> From what you're saying it doesn't sound like the savings are all that significant for the liner.  I ended up paying $385 for a 25' liner, appliance connector, and rain cap, with no tax and free shipping.  Granted, I had to negotiate a little over e-mail with the ebay seller, but given how much longer my liner was and the inclusion of the rest of the kit I think I did well, and without the hassle of piecing together multiple lengths of rigid liner.
> 
> Where your advice could have definitely saved me money would have been in the insulation, but if that's 2 inches thick it wouldn't have worked well for me anyway.  My flue was 11" x 11" and it was hard enough to cram the liner down it as it was.  Adding insulation that thick would have made it practically impossible.
> 
> On that note, I may buy some roxul and line my firebox with it.



what's the thickness of 8in liner purchased for $385 shipped? 
when shopping what I found were mostly flex liner kits with .007in thickness stainless.
no question flex liner will be easier to install vs rigid ..

not everyone has the luxury of having access to a fireplace warehouse with decent inventory.
same for large commercial building supplier that stocks correct high temperature insulation.

mineral wool insulation rated at 2000f comes in several different thickness/shapes including 1in rolls.
Lowes can order correct insulation but they will need help in finding part numbers/descriptions.


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## a316co2000 (Mar 12, 2014)

_CY_ said:


> what's the thickness of 8in liner purchased for $385 shipped?
> when shopping what I found were mostly flex liner kits with .007in thickness stainless.
> no question flex liner will be easier to install vs rigid ..
> 
> ...



I think it was .006...whatever the standard 1-ply SS liners are, but it met UL specs.


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## bholler (Mar 12, 2014)

yeah .oo6 is the standard light wall liner thickness


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## a316co2000 (Mar 14, 2014)

Well yesterday it was about 32 degrees outside and VERY windy (20 degrees with wind chill) most of the day, so I figured it was a good day to test the capability of the stove.  I came home on my lunch break and followed all the instructions I've read online for using catalytic stoves (got a nice hot fire going, let the stove heat up, then closed the cat bypass and air "intakes" on the front).  I turned the heat off but left the furnace fan on to circulate the air throughout the house.  It's a 2-story colonial and one of the two air returns is on the main level just outside the room the stove is in, so I wanted to see if this method helped move the air around.

When I turned the heat off it was 70 degrees in the house; when I got home a few hours later it was 68 degrees in the living room (which is located on the opposite side of the house with hallways in between, restricting the flow of air).  I also went upstairs and it felt pretty comfortable up there as well.  I have a 2-year old so when she got home I used a small space heater in the living room to bring it up a couple more degrees in there, but it only came on occassionally.  The rest of the bottom level was plenty comfortable enough thanks to the stove.  I don't have a thermometer in there but I would think it had to be at least 75 degrees.

Before bed I loaded it up as full as I could get it (also did this around 4:30 pm) and after about 20 minutes closed the cat bypass again.  I turned the heat on just in case, but left the fan on full time (as opposed to keeping it on auto) to keep moving the heat from the stove around.  This was at 10:30 pm.  This morning I woke up and came downstairs at 7, and the blower to the stove was still on putting out a small amount of heat.  A couple mostly burned logs remained in the stove from the night before, so I put some kindling in and loaded it up again, 20 minutes later closed the cat bypass, and told my wife to turn the heat off when our daugther wakes up and comes downstairs.

Overall I'm pretty happy with my free stove and $625 insulated liner kit.  I'm still kind of learning how to work the stove (though I think I have a pretty good handle on it), but I was able to get a load to burn for 8.5 hours and be the primary heat source for a 2,000 sqft, 2-story house with a floor plan that is anything BUT open, all in sub-30 degree weather.  Oh and I'm using what I was told is seasoned oak, but I believe it to be poplar.  Before and after pictures still to come for anyone interested.


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## begreen (Mar 14, 2014)

Poplar is much lighter than oak and has a clear, greenish tinted grain. If that is poplar you are going to be in for a big surprise when switching to oak. Just be sure the oak has had a couple years of seasoning since it was split and stacked.


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## oconnor (Apr 2, 2014)

_CY_ said:


> yes .. mineral wool rated to 2000f is material used for liner insulation. follow link in above post for rest of details.



No, it isn't. Liner insulation wrap is ceramic fiber. Mineral wool isn't rated for use at 2000. It melts at that temp in its purest form. 

It is a discussion of technicalities. You will not find a manufacturer of mineral wool that will tell you to insulate your flue with it.

It does meets code in Canada as a material for a block off plate, butt in that instance, it is open to cooling on one side.


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## oconnor (Apr 10, 2014)

The material you are linked to is used to provide additional escape time in the event of a structure fire. It is intended to be used for this purpose once, during a fire. It is tested to ASTM E136, which you can look up. It is not tested in the application you are describing.

The test for liner installations involves repeated chimney fire simulations, and in Canada involves 2100F temps. Insulating a liner involves following the manufacturers instructions, otherwise you are experimenting, and do not meet the ULC specs.


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## oconnor (Apr 10, 2014)

Here is a link to a product that is intended for chimney liner use. You will note that it specifically states a max continuous operating temperature vs a melting point.

 http://www.morganthermalceramics.c.../kaowoolblankets-kaowoolblanketszrenglish.pdf


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## chimneylinerjames (Apr 10, 2014)

oconnor said:


> Here is a link to a product that is intended for chimney liner use. You will note that it specifically states a max continuous operating temperature vs a melting point.
> http://www.morganthermalceramics.c.../kaowoolblankets-kaowoolblanketszrenglish.pdf



Yes this is the proper type of insulation intended for use with a chimney liner, with a foil backing.  This insulation, called many different names by many different manufacturers, is UL listed with the use of a chimney liner and being safe in the event of a chimney fire. Chimney fires can exceed 2100*.  This insulation is rated to exceed that.

A wool type insulation, or the like, is great for block of plates.  It is not UL listed with the use of a chimney liner.  It sill can help definitely with keeping the flue warm, but it is NOT UL listed with a chimney liner.


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## fire_man (Apr 10, 2014)

ChimneyLinerJames has it right, the need for a 2000 F rating is to meet UL standards in the event of a chimney fire. Yes it's a worse case scenario, but that's where the rating comes from. Not everybody installs to code.

My guess is if you had a chimney fire, no insulation might be better than the wrong insulation.


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## BrotherBart (Apr 10, 2014)

_CY_ said:


> my liner is insulated to be safe in excess of 1,100C with added safety of being inside a masonry fireplace several feet thick.



Would love to see pics of a fireplace "several feet thick" much less the chimney on it which is where the concern would be.


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## bholler (Apr 10, 2014)

_CY_ said:


> my liner is insulated to be safe in excess of 1,100C with added safety of being inside a masonry fireplace several feet thick.



You may be right that it is safe but it was never tested by any one for that purpose and it is not approved for it.  Even though it migh be safe it should never pass an inspection and if there were a fire your insurance company will likely deny your claim due to using unlisted materials in the install


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## bholler (Apr 10, 2014)

I don't think anyone is saying that it is not safe.  But we are all saying it does not meet code and telling other people to do installs that do not meet code is irresponsible.  And by the way you may have several feet of masonry on the sides but not on the front where the roof framing meets the chimney it looks to me like you only have about 6" to 8" there.


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## BrotherBart (Apr 10, 2014)

Somewhere in all of this the OP's question has probably been answered.


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