Kaowool behind the insert

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Rockey

Minister of Fire
Dec 18, 2007
807
SW Ohio
Good idea or bad idea? I figured that it would keep the heat from being absorbed by the back of the hearth and transfered right outside. Will this help any?
 

Haston

Member
Feb 21, 2006
56
For what it's worth, I am using kaowool as a "soft" block off plate this winter on my Regency i3000 insert-- and have been impressed with how much better the stove is burning. I know I need to make and install a proper sheet metal plate, but the kaowool is doing some good, it seems. Granted, I have an interior chimney and a full, insulated liner, but the wool may very well work out for your application. H.
 

Gooserider

Mod Emeritus
Nov 20, 2006
6,737
Northeastern MA (near Lowell)
Rockey said:
Good idea or bad idea? I figured that it would keep the heat from being absorbed by the back of the hearth and transfered right outside. Will this help any?
A sheet metal blockoff plate is the biggest thing, but Kaowool behind the insert can also be a BIG help, if you have an exterior chimney or other construction where the heat radiated out the back side of the chimney won't be useful.
If you have an internal chimney it doesn't help all that much.

Gooserider
 

karl

Minister of Fire
Apr 9, 2007
1,058
Huntington, West Virginia
Where can you get kaowool or something similar? Would I be able to find it locally? Like at Lowe's or Home Depot? What about other smaller stores? What would I like for.

Is rockwool the same thing? Or atleast usable too?
 

Rockey

Minister of Fire
Dec 18, 2007
807
SW Ohio
karl said:
Where can you get kaowool or something similar? Would I be able to find it locally? Like at Lowe's or Home Depot? What about other smaller stores? What would I like for.

Is rockwool the same thing? Or atleast usable too?
I bought 25' of Kaowool on ebay it is rated up to 2300 degrees. I don't know if Lowes or Home Depot sells it just make sure it is a high temp rated ceramic product. i paid $47.00 with shipping for mine.It is also known as ceramic blanket and it worked great.

I put some behind my insert last night and on top of the insert behind the front plate and it worked great. the heat coming out of the blower was much higher and it heated the room/house up a bit quicker. I think it will really help on those nights that I struggle - 20 degrees and lower. Heating 2700 sq feet with one medium sized insert takes learning every trick there is out there. i am debating fabricating my own OAK for next season since my house in newer and fairly airtight.
 

PAJerry

Member
Feb 12, 2006
226
Waterford, PA
I did the top and sides of mine and it works great. Just be careful not to block the air intake - PE has theirs for 'outside' air on the lower back of the unit, and 'inside' air is on the right side of the unit. When I first posted this 'modification', it was pretty much panned, but, by golly, it WORKS. :>)
 

BrotherBart

Modestorator
Staff member

milner351

Member
Feb 13, 2008
104
Belleville, MI
I'm having a hard time finding roxul, rockwool, or anything close to it, the local hardware that has lots of stoves and stove accessories for sale does not carry it, neither does home depot -- any suggestions?


Is it advisable to put some of this above the block off plate AND around all sides of an insert (if there's room for it)

I have a summit in an outside chimney - and I'm fighting an uphill battle to get more heat out of it.
 

woodzilla

New Member
Dec 23, 2007
168
Mid-Michigan
what thickness are you all using?
 

woodzilla

New Member
Dec 23, 2007
168
Mid-Michigan
[quote author="milner351" date="1203659521"]I'm having a hard time finding roxul, rockwool, or anything close to it, the local hardware that has lots of stoves and stove accessories for sale does not carry it, neither does home depot -- any suggestions?


Is it advisable to put some of this above the block off plate AND around all sides of an insert (if there's room for it)

I have a summit in an outside chimney - and I'm fightin an uphill battle to get more heat out of it.[/quote


Hi milner, I was told by member jtp10181 to use the insulation above the block off plate.
 

brooktrout

New Member
Dec 23, 2007
376
Hamden, NY
My insert has a small box/fan unit attached to the back of the insert- I was thinking of doing the same thing, but I'm worried about enough circulation around that unit to keep it operating properly. What do you think?
 

Gooserider

Mod Emeritus
Nov 20, 2006
6,737
Northeastern MA (near Lowell)
Generally there are several "layers" to an insert... You have the firebox itself, which generally sits inside of a shell that has a gap between itself and the firebox, and which is normally the space that blowers will circulate air through - the shell may have some insulation in it, or might be a steel box, and is the "box" that must be fit into the fireplace. Air doesn't get intentionally circulated around the outside of the shell so essentially anything that gets past the shell is "lost" heat. Thus putting rock wool or other fire proof insulation into the space between the shell and the fireplace should not interfere with your blower airflow, or the convection heating, but should help keep the heat in the space between the firebox and the shell where the blower can pick it up as part of the convection airflow. However you do need to be careful not to block any air intakes or other important bits.

With an inside fireplace / chimney, it doesn't make a lot of difference since the heat that gets into the masonry will still mostly warm the house, but with an exterior fireplace it can be very worth while to line the inside of the firebox and the area above the blockoff plate in order to keep as much heat as possible inside the unit instead of escaping to the outside through the un-insulated masonry.

Gooserider
 

rickw

New Member
Feb 24, 2007
142
I used rockwool insulation from McMaster-Carr. It came in 2" thick sheets, which I wrapped around the top, sides and back (held on with soft steel wire). My Answer insert burns much cleaner and is generally a lot less fussy in operation. Maximum burn times are not improved, but its much easier to use. The glass stays clean, too.

It cost about $20 per 2'x4' sheet, 2" thick (plus shipping) Search the website for "semi-rigid mineral wool insulation ". You might want to use a mask while you're fitting it up.

Another addition was a magnetic thermometer; I think good clean burning needs about 600 degrees surface temp. Sometimes it goes as high as 800, which I consider pushing the envelope. I've never seen a glow from inside the shroud, at least. Don't load it and walk away until you see how it runs with the new insulation; please remember that there is risk in making the stove operate a little hotter. You need to evaluate that risk for yourself.

Good Luck.

If I could figure how to post pics..
 

karl

Minister of Fire
Apr 9, 2007
1,058
Huntington, West Virginia
Take a look at the pics I posted in the topic "Interior chimneys and insulation". I'm hoping insulation will help my problem.
 

Stevebass4

Minister of Fire
Nov 18, 2006
845
Franklin MA
how do you guys mount the Kaowool to the fireplace itself? some sort of high temp adhesive? or did you tapcon it in place?
 

Gooserider

Mod Emeritus
Nov 20, 2006
6,737
Northeastern MA (near Lowell)
Stevebass4 said:
how do you guys mount the Kaowool to the fireplace itself? some sort of high temp adhesive? or did you tapcon it in place?
Past discussion has varied, probably alot depends on the exact nature of the stuff, it comes in different forms ranging from a fairly stiff board to a fiberglass like bat... The big issue is mostly to hold it in place long enough to get the insert into place, as once the insert's installed, the Kaowool isn't going anyplace.

The rigid material tends to get tapconned to the inside of the fireplace, while people using the softer material may either wire it to the fireplace, or to the outer shell of the insert - it's not a critical issue as long as you can hold it in place, and there are a lot of variables depending on the details of your individual installation.

Gooserider
 

Stevebass4

Minister of Fire
Nov 18, 2006
845
Franklin MA
Thanks just ordered two sheets of 2*4*1inch stuff from McMaster Car though work and i'm pretty sure it's fiberglass like bat stuff.. so the plan is to line the inside of the brick (exterior chimney) with the stuff - and then slide the insert back in - wonder if they sell high temp duck tape stuff
 

Gooserider

Mod Emeritus
Nov 20, 2006
6,737
Northeastern MA (near Lowell)
Stevebass4 said:
Thanks just ordered two sheets of 2*4*1inch stuff from McMaster Car though work and i'm pretty sure it's fiberglass like bat stuff.. so the plan is to line the inside of the brick (exterior chimney) with the stuff - and then slide the insert back in - wonder if they sell high temp duck tape stuff
Not sure... I know they make a "Kaptan" tape (unsure of the spelling) that is used in electronics to mask circuit boards going through a wave solder machine, but I have no idea if that would be useable for this application. They also make high temperature tape that is used in pellet stove installs, but I don't know if it has a high enough temp rating to be useful / safe.... I'd be looking through McMaster's catalog in the same area as the insulation was to see if they list any kind of tape suitable for use with it....

Overall, I'd be less worried about lining the chimney than I would be about lining the inside of the firebox below the blockoff plate (You ARE using a blockoff plate, aren't you?) If I was trying to line the chimney, I'd do it by using an insulated liner.

Gooserider
 

Stevebass4

Minister of Fire
Nov 18, 2006
845
Franklin MA
Thanks again for your help Goose!

i already have a block off plate and i use a "direct connect" for my insert (goes about 6 feet into the terra cotta flue) but the plan is to use the Kaowool on the sides and back of the fireplace and then slide the insert back in

my exterior chimeny is in fine shape but there is a crack that runs to the smoke shelf - so i figure if i insualte the fireplace before i stick the insert back in - i wont lose any heat from the crack and to the outside brick
 

Gooserider

Mod Emeritus
Nov 20, 2006
6,737
Northeastern MA (near Lowell)
Stevebass4 said:
Thanks again for your help Goose!

i already have a block off plate and i use a "direct connect" for my insert (goes about 6 feet into the terra cotta flue) but the plan is to use the Kaowool on the sides and back of the fireplace and then slide the insert back in

my exterior chimeny is in fine shape but there is a crack that runs to the smoke shelf - so i figure if i insualte the fireplace before i stick the insert back in - i wont lose any heat from the crack and to the outside brick
Well, the blockoff plate is good, but IMHO direct connects are problematic at best. Insulating the fireplace will help keep you from loosing heat out the back for sure, but replacing that direct connect with a full length liner will probably improve your performance, and make future maintainance a LOT easier...

1. With a Direct, you are supposed to remove everything for cleaning in order to get the creosote etc. that falls down between the chimney and the connector pipe - otherwise it can build up and cause a chimney fire. With a liner, you normally don't have to remove anything for cleaning - take the baffle out of the insert, close the doors, brush down the liner, and clean the crud out of the stove, about as easy as it gets...

2. Most chimneys are larger than they should be to service an insert - you probably have a 6" diameter flue exit - codes say that you shouldn't have a flue more than 1.5x the cross sectional area of the flue exit on an outside chimney - anything larger than about an 8x8" square tile flue is way to big (the 8x8 is marginal) - going to the right size liner, especially if it's insulated, will improve your draft significantly. Remember it's the chimney that makes your stove work, so it's important to get that right...

3. A "crack that runs to the smoke shelf" is not consistent with "a chimney in fine shape" - I'd seriously reccomend trying to patch the crack (preferably after consulatation with a mason as to materials and methods) as preferable to just trying to insulate over it... A full liner will also ensure that even with the crack you are still reasonably fire safe.

4. With a direct connect, you don't want to put any sort of insulation above the blockoff plate - it will rapidly soak up any liquid creosote and become a potential fire hazard and a real mess to deal with, especially if you get any rain or snow entering the chimney and adding to the mess. With a full liner there is no creosote exposure, so the insulation will stay clean.

Gooserider
 

Stevebass4

Minister of Fire
Nov 18, 2006
845
Franklin MA
1) i agree a full liner would be better BUT when this QF 2100i was sold all that was needed was a direct connect and i've been running it for two years now

1a) yup i have to remove everything to clean the direct connect pipe, the stove and the terra cotta flue tires sure it's a PIA but it only takes about 2 hours

2 i think my flue tiles are like 12*8

3) the chimeny has been checked and they fireplace guy said it was everything fine :shrug: there is no crack in the chimney section where the flue is (if this makes sence)

4) great thanks for the info - i wont put the stuff above the block off plate

maybe i should ask elk to come by and have a look one of these days
 

Gooserider

Mod Emeritus
Nov 20, 2006
6,737
Northeastern MA (near Lowell)
Stevebass4 said:
1) i agree a full liner would be better BUT when this QF 2100i was sold all that was needed was a direct connect and i've been running it for two years now
US Codes do technically allow direct connects, My understanding is that the Canadians don't, and I tend to think they have more practical experience as to what works best...

1a) yup i have to remove everything to clean the direct connect pipe, the stove and the terra cotta flue tires sure it's a PIA but it only takes about 2 hours
That's doing pretty good, but I'd bet a liner would take half or less than that, other than the time it takes to dig out and setup all the tools...

2 i think my flue tiles are like 12*8
Pretty sure that's well over the "OK size" for an outside chimney - a 6" diameter stove pipe is about 30sq" in cross section, a 12" x 8" tile is about 96sq", or about 3x the area

3) the chimeny has been checked and they fireplace guy said it was everything fine :shrug: there is no crack in the chimney section where the flue is (if this makes sence)
Sort of, and obviously the chimney guy has seen it, while I haven't, but it still doesn't sound good to me...

4) great thanks for the info - i wont put the stuff above the block off plate

maybe i should ask elk to come by and have a look one of these days
If you see Elk say hi for me! I'm willing to bet that he will say about the same thing that I just did - a good bit of what I've learned on these forums came from his advice, I just try to put it a bit more diplomatically. :coolgrin:

Gooserider
 

iceman

Minister of Fire
Nov 18, 2006
2,381
Springfield Ma (western mass)

Funk Brother

Member
Aug 31, 2007
36
Near Dayton Ohio
Folks - this is my first post so I apologize in advance if I mess something up. The question of how to get the most heat from an insert/stove is one that is near and dear to my heart. And my (current) solution includes the use of Kaowool. By the way, I got mine from McMaster.com, under the category thermal insulation/flexible ceramic insulation/ultra high temperature sheets. It came in a 24 inch x 25 foot roll.

I own an Avalon Olympic (with blower) and started out - four winters ago - with the usual insert setup using panels to block off the portions of the fireplace opening not filled by the insert. I was disappointed in the heat I was getting from the stove. By the way, my stove is located in an fireplace on an exterior wall in the lower level of a tri-level ranch, using a full 6" flexible liner which runs up about 20 feet. I decided I was loosing too much heat to the firebox bricks hidden behind the shrouding, and perhaps up the chimney as well. I first tried covering the back and top of the insert with the ceramic insulation. That helped the stove get hot faster and stay hot longer, but I still wasn't happy with the amount of heat the stove was kicking out. And yeah, I know there are different kinds of heat, but I prefer the kind that feels like the sun. Radiant heat.

I'm attempting to attach a picture which shows what I ended up doing. Basically insulating the old fireplace firebox whit the ceramic insulation (top and sides), held up by sheet metal tapconned into the masonry. I also added a damper above the stove. This may not be the ultimate solution, but I think it has increased the heat output a lot. Hope this helps someone else.
 

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