Insulating behind wood insert

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darktower007

Feeling the Heat
Oct 16, 2018
281
Chattanooga
Hey folks
I was needing some help on how to insulate around the insert. I’m in the planning stages of buying an insert. I’m looking at a few units such as Fireplace Xtrodinare Large flush units and Blaze king. My unit will service an area of 1245 sq.ft inside a brick fireplace clay flue. The chimney faces north.
The opening is 25” deep 27” tall and 40” wide.

My question is to maximize room heating should I use Roxul bats... cut them to fit, install block off plate and that’s it? If anyone has any links or photos that would be great too.
Thank you



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[Hearth.com] Insulating behind wood insert
That’s what I did. Insulated block off plate, and Roxul bats cut to fit tight for the walls. It made a big difference.
 
What's in there now? Are all the heaters past?
 
What's in there now? Are all the heaters past?

Currently just door insert and some crude blower. The chimney was scoped last year and clean as a whistle... but chimney said don’t use it. I didn’t plan on it, as I’m going with an insert and lined flue.

That Roxul stuff looks perfect, but I wonder is there any particulate shedding off the bats that can get into the room?


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That Roxul stuff looks perfect, but I wonder is there any particulat
There’s a few inserts that don’t have a solid convection jacket surrounding the firebox. Only a few though. On most inserts there’s no way for the blower to pick up any fibers from the Roxul.
 
Wow that looks great!


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It turned out pretty good. I’m not a fan of the brass, but the price was right.
 

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That's a big stove, but the huge stone wall dwarfs it.
 
Cool, that will be interesting. Do you have good access to a long term supply of NIELs or HomeFires? Or maybe they will have a brick version out by then?
 
Bumping this old thread because I've never seen this done or recommended before, but it seems like a good idea. I had also never heard of Roxul before considering an insert but I've since learned a lot about it and this seems like a perfect application. For my insert installation (also in a masonry fireplace with a north facing chimney) I would plan on packing as much Roxul as I can above the blockoff plate/around the liner as well as below the block off plate and on the floor and sides of the firebox. Just making sure that I'm not overlooking any potential code issues, etc...?
 
Bumping this old thread because I've never seen this done or recommended before, but it seems like a good idea. I had also never heard of Roxul before considering an insert but I've since learned a lot about it and this seems like a perfect application. For my insert installation (also in a masonry fireplace with a north facing chimney) I would plan on packing as much Roxul as I can above the blockoff plate/around the liner as well as below the block off plate and on the floor and sides of the firebox. Just making sure that I'm not overlooking any potential code issues, etc...?
Is your liner insulated? This is what I do for inserts typically. It is leftover liner insulation.
 

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Is your liner insulated? This is what I do for inserts typically. It is leftover liner insulation.

I haven't gotten there yet-still researching inserts but leaning toward the Montlake 300- just ran across this while searching. I've watched a few insert install videos etc ...and most just put the insert into the firebox with no insulation at all. I want to keep as much heat as I can radiating into the room rather than absorbing into the structure of the chimney.
 
Roxul with foil face 2" thick. Back wall and top 4" thick and the walls 2". Cut to fit and no fasteners needed to hold it in. It is pretty rigid and cuts nice. Insulated liner. Didn't see much of a difference so far after doing this but maybe it needs a metal plate below the insulation on top?
 

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Roxul with foil face 2" thick. Back wall and top 4" thick and the walls 2". Cut to fit and no fasteners needed to hold it in. It is pretty rigid and cuts nice. Insulated liner. Didn't see much of a difference so far after doing this but maybe it needs a metal plate below the insulation on top?
Did you tape the seams?
 
No I didn't. Wasn't sure if any foil type tape would stick. Any suggestions?
Do you think I need a metal block off plate below the Roxul? Foil face maybe not enough barrier?
The foil should be fine but it needs taped
 
Hi, new burner here with a related question. Have a PE Neo 1.6 incoming whenever the model gets processed by EPA ...rumored after the first of the year (been waiting since July...ugg). It going into an untiled exterior brick chimney/fireplace on a 1918 economy craftsman in the PNW heating about 750 sq ft of 1100 sq ft. The plan: Insulated liner, insulation around the insert and block off plate. The installer recommends insulate with K-wool around the insert. In back there will be about 2" of clearance, the sides there is only 1.75" clearance and on top a 6" of clearance between the insert and the brick fireplace. I am going to template the block-off plate and buying the K-wool.

So the questions are:
Is the insulation really needed to prevent the bricks acting as a heat sink? (I presume that the insulation will help).
Will the insulation be effective at putting more heat in to the room?
So with the clearances of inseret to fireplace, should I get 1" or 2" K-wool and should it be foil faced?

Thanks and much appreciation!
Warm and Happy Holidays
 
Sounds like our old house on Queen Anne. Yes, the insulation behind the insert will help reduce heat loss to the exterior brick meaning more heat into the house from the insert. One inch kaowool should suffice in our climate. Foil-faced is fine.