Does anyone "insulate" their masonry fireplace before installing an insert?

[joefrompa]

Hi all,

I have a fireplace that is sitting in an exterior wall with a chimney running up the side of my house. Getting an insert installed in 3 weeks and thinking of things I want to tackle beforehand.

One area I was wondering about: heat is going to be radiating out from the back and back-sides of the insert through the masonry. That will simply be heat-loss to me, as it will radiate to the outdoors.

My insert will leave some room in the fireplace. Is it possible to place either insulatory or heat-reflective materials in the BACK of the masonry fireplace so that it keeps the heat radiating towards the house (and keeps the insert steel and surrounding masonry warmer)?

Thanks all,

Joe

 

[Dune]

Good post Joe. There was a similar discussian last year. I think you have a good point but lets see what the big guns say.

 

[vvvv]

blower covers the bases. masonry is conductive. al foil worx great

 

[guest5234]

Hi all,

I have a fireplace that is sitting in an exterior wall with a chimney running up the side of my house. Getting an insert installed in 3 weeks and thinking of things I want to tackle beforehand.

One area I was wondering about: heat is going to be radiating out from the back and back-sides of the insert through the masonry. That will simply be heat-loss to me, as it will radiate to the outdoors.

My insert will leave some room in the fireplace. Is it possible to place either insulatory or heat-reflective materials in the BACK of the masonry fireplace so that it keeps the heat radiating towards the house (and keeps the insert steel and surrounding masonry warmer)?

Thanks all,

Joe

It is madness to have a Chimney thay runs on the outside of the house....why do builders do it?
In answer to your question, you can put some sheet metal at the back of your stove to reflect the heat back into the room, I have a sheet that is fixed a littel of the walll with spacers and the wall behind it stays cool with all the heat reflected back into the room.

 

[burleymike]

Good question my insert should be here next week sometime and I am thinking about the same thing. I know one thing for sure I am going to build a block off plate to prevent heat from being absorbed by all that masonry.

"It is madness to have a Chimney thay runs on the outside of the house....why do builders do it?
In answer to your question, you can put some sheet metal at the back of your stove to reflect the heat back into the room, I have a sheet that is fixed a littel of the walll with spacers and the wall behind it stays cool with all the heat reflected back into the room."

I think builders do that because they don't have to live in the crap they design. Funny thing is my house the builder did not put in a fireplace the previous owners thought it would be nice to have one build on an exterior wall. Only problem is they also thought a tall chimney was ugly so it is 4' too short, these people could only see form and not consider function.

 

[spirilis]

yeah, I'm betting it's a hard sell to the uninitiated American house buyer to have a house at X sqft built but a number of sqft taken up by a huge brick structure when you can "just build it on the outside like everyone else!" and reclaim that space . . .
when the priority behind the fireplace is only ambiance, that is a reasonable tradeoff to make as interior space is obviously more important to them than their fireplace ambiance.

someday perhaps this will change, but I don't see it. Having an insulated chase around the exterior chimney could be an acceptable fix though IMO. But then many see the big brick chimney structure as part of the house's look, too...

 

[burleymike]

It seems that most new houses at least around here don't have any chimney at all they just have a zero clearance direct vent gas heater or uh fireplace .

The house I grew up in had an exterior fireplace that was really good at keeping the air in the house smelling like creosote. Before my dad put in a smoke dragon they had glass doors on the fireplace. I remember as a little kid coming down the stairs into the family room in the winter months and seeing a couple inches of ice on the glass doors. That family room was always so cold because of that big masonry heat sucker. The fireplace and the brick around it would be wet with condensation. The smoke dragon sure did make a mess of the 12x12 clay liner tiles though.

 

[midwestcoast]

I have similar FP & Chimney. I lined the FP walls with a layer of rock-wool, cut sheet metal to fit & fastened it to FP walls with a few tapcons in the mortar joints. Sheet metal holds the rockwool in place & reflects radiant heat back to the insert. I also put heavy duty Aluminum foil on the floor & wherever wasn't covered by the sheet metal. Pretty easy.
If you're making a good block-off plate you'll prob be working with sheet metal & rock-wool or Kaowool already anyway so why not? I like to keep the heat INSIDE my house.
FYI after a couple hours burning I can still feel heat on the exterior of the masonry, but I try not to obsess about that.

 

[begreen]

Good question my insert should be here next week sometime and I am thinking about the same thing. I know one thing for sure I am going to build a block off plate to prevent heat from being absorbed by all that masonry.

"It is madness to have a Chimney thay runs on the outside of the house....why do builders do it?
In answer to your question, you can put some sheet metal at the back of your stove to reflect the heat back into the room, I have a sheet that is fixed a littel of the walll with spacers and the wall behind it stays cool with all the heat reflected back into the room."

I think builders do that because they don't have to live in the crap they design. Funny thing is my house the builder did not put in a fireplace the previous owners thought it would be nice to have one build on an exterior wall. Only problem is they also thought a tall chimney was ugly so it is 4' too short, these people could only see form and not consider function.

The reason builder's do it is because homebuyer's no longer are thinking of the fireplace as an important heat source. Instead, it's all about the visuals and aesthetics. The net result is a bad start if you are trying to get back to the common sense designs of when heating a house with wood was pretty much the only option.

 

[woodgeek]

Air tight block-off plate (always) + some high temp batts (e.g. kaowool) above the plate and behind insert.

 

[joefrompa]

Thanks guys. I wonder if the chimneysweep/installer is going to give me any headaches, but I really like the idea of some simple heavy duty aluminum foil and some high temp kaowool/rock wool (can I get that at home depot???)....

Seems like the sheet metal options are nice heavy duty option, but doesn't need to be done.

 

[daryl]

I installed a insert in a basement fireplace on a outside wall once and could not make it heat for anything. Until we insulated the firebox with foil faced kaowool. I don't think you can get kaowool at Home Depot though.Most hearth shops can get it.

 

[FireAnt]

I insulated my pipe going up my chimney. The outside of my chimney is inside my garage.

 

[begreen]

Just for a twist, my BIL constructed his large stone fireplace by creating an outer stone shell with a gap between it and the actual chimney. This gap is filled with vermiculite. From the outside or inside you would never know it is an insulated fireplace.

 

[granpajohn]

Someone here on Hearth.com posted some good photos of his insulated insert install. I don't know how to find that thread, but I was so impressed with it that I saved a photo. I apologize to the original poster, but in the interest of science I will show it here. If the owner pops up....please give him all the credit. (It's an Avalon, BTW)
Edit to add: he used some sort of heat tolerant insulation, covered with corrugated steel, painted it all black. I believe he used tapcons to hold it all to the masonry.

 

[weatherguy]

Someone here on Hearth.com posted some good photos of his insulated insert install. I don’t know how to find that thread, but I was so impressed with it that I saved a photo. I apologize to the original poster, but in the interest of science I will show it here. If the owner pops up….please give him all the credit. (It’s an Avalon, BTW)

Thats why I love reading this site, some very clever and creative people here.

 

[granpajohn]

Upon reading the thread more closely, I think MidWestCoast has given a good description of how it was done.

 

[vvvv]

the masonry that goes thru the ceiling & contacts the exterior cold is a great conductor for heatloss. insert should have a blower to blow hot air away from the masonry/monolith. insulated liner also

 

[midwestcoast]

Upon reading the thread more closely, I think MidWestCoast has given a good description of how it was done.

Yep, I sorta followed another install from here, but can't find the thread now. I think that one was on a Hearthstone Clydsedale in a very big fireplace and the author painted the sheet metal black. Anyone able to un-earth it??
ps. I got the rockwool out of my own attic since it's not the easiest to buy. I was about to blow cellulose all over up there anyway so no harm.

 

[joefrompa]

Guys, when I check out Kaowool on Amazon I see it for $90 (for a pack).

Rockwool is sold in cubes and appears to be used for hydroponics. Anyone have a recommendation on where to get it commercially in sheets or batts?

Also, it seems like I could simply line the masonry with rockwool. Do I NEED to physically attach it to the masonry via something like sheet metal + tapcons.

I don't have a hammer drill, so I'm trying to figure out ways to avoid needing to set something into the masonry.

 

[btuser]

I cook in metal pans. Sometimes I cover the top with aluminium foil and gosh, the food still cooks. Don't confuse radiant/convective/conduction heating with each other. I can see insulating the firebox but what the heck is aluminium foil going to do?

 

[vvvv]

I cook in metal pans. Sometimes I cover the top with aluminium foil and gosh, the food still cooks. Don't confuse radiant/convective/conduction heating with each other. I can see insulating the firebox but what the heck is aluminium foil going to do?

al foil reflects radiant heat. it works well for the sides of the stove, not very well above the stove because then more convective heat is involved. my stove currently sits 6" from block chimney which got really hot be4 i put al foil behind it & made quite a diff. so its still there though its ugly

 

[zzr7ky]

I really like the install picture above.

I studied hard on this and just couldn't bring myself to do it.

In the end I installed a freestanding stove just in front of the fireplace opening. I also added about 20 bricks spaced an inch off the fireplace back and side wall to provide some thermal mass and keep more heat in the home.

I'd like to add a couple of inches of insulation behind my loose brick heat sink. I know it would help.

All the best,
Mike

 

[begreen]

I cook in metal pans. Sometimes I cover the top with aluminium foil and gosh, the food still cooks. Don't confuse radiant/convective/conduction heating with each other. I can see insulating the firebox but what the heck is aluminium foil going to do?

al foil reflects radiant heat. it works well for the sides of the stove, not very well above the stove because then more convective heat is involved. my stove currently sits 6" from block chimney which got really hot be4 i put al foil behind it & made quite a diff. so its still there though its ugly

Methinks the foil is just acting as a wall shield. The same effect will happen if you use cement board. That is not the same as reducing heat loss to the masonry in a firebox. The difference being you are just keeping the wall cooler by the convection of air behind the shield. In the fireplace you are trying to prevent heat loss in a closed cavity.

 

[tickbitty]

ebay, Kaowool insulation $7 per foot. There are other deals on there as well for a whole roll, and etc.

http://cgi.ebay.com/Kaowool-Insulat...887?pt=LH_DefaultDomain_0&hash=item20b36ca387

If you needed 2 X 4' though, that would cost you $56 and somebody else on there has a 25' long roll of 24" wide for 62$ so just look carefully!
http://cgi.ebay.com/Kaowool-RT-Cera...111?pt=LH_DefaultDomain_0&hash=item2a0a869ef7

This site also has it cheaper, plus heatproof/insulating caulks and paints with insane R values.
http://shop.clay-planet.com/inswool.aspx