Is Fiberglass Batt Insulation Safe to Use Inside a Stove

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spiker
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Post by spiker » Fri. Feb. 19, 2010 8:33 am

I did not find much discussion on using fiberglass batt insulation inside a stove, so felt it worth opening a new topic. In the post below (about refurbishing my Citation stove) I note that there are 1 inch gaps where air can bypass the grates and I am looking for a simple way to plug them.

Refurbishing a Salvo Citation

The gaps in question are in the corners of the grate area where they would not be in direct contact with the fire, but would obviously still be subject to a lot of heat. I propose to only use the batt material, with no paper backing. In researching the fire hazard of fiberglass insulation, I read that it is not flammable, being made of sand ultimately, but there is concern over formaldehyde and resins that are used in the manufacturing process. I read that the melting point is over 3000 F, so that does not seem to be a concern.

I also read that rock wool insulation is even more fire resistant - being made from rock. I have never seen it in stores, not that I was looking.

I am sure that there are preferred alternatives, and I am interested to hear them, but I figure the discussion will benefit everyone.

Now don't go all batty on me, I am asking for advice because I am concerned. If nothing else, this should generate some spirited conversation.

 
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Post by CapeCoaler » Fri. Feb. 19, 2010 9:14 am

Are you talking about the gap from...
The 'Gaps in air control from ash tray' picture...
If so rope gasket would work...
The fiberglass batt would let air past it...
Waterglass adheasive would make it stick...
**Broken Link(s) Removed**You could also top the gasket with 'stovo'...
**Broken Link(s) Removed**But I think with all the movement of the grates it will flex the hardened cement too much...

You will only slow down the air flow thru that gap not stop it...
Too much movement...

 
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Post by spiker » Fri. Feb. 19, 2010 9:33 am

The gap along the front of the grates I agree can be sealed with a rope gasket, and I intend to do so. The additional roughly 1 in square gaps I am talking about are in the corners of the stove at the level of the grates and not visible in any of the posted pictures. Sorry no good picture right now, I'll try to post something later.

I also agree the insulation would only slow the air flow. If I pack it tightly, I think it would provide as much resistance to air flow as the fire-bed itself, and be reasonably effective. Then I could consider a more effective solution before the next heating season.

 
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Post by LsFarm » Fri. Feb. 19, 2010 9:51 am

You can use fiberglass stuffed into a hole to seal off most air movement. It may not last very long, it could be dislodged by poking the fire or the coal movement when you shake down your ashes.
But fiberglass stuffed in the gap will work.

Greg L

 
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Post by spiker » Fri. Feb. 19, 2010 12:11 pm

OK, so far no-one has called me crazy, so I'll use this as a quick fix to get up and running. I'm thinking that fitting some fire brick pieces into the gaps with furnace cement or sealant will be a good long term solution.

Guess I was wrong about the spirited discussion part. Oh how the ego suffers. Maybe tonight after people get home from work.

I added a photo of the air gaps to my other post linked below. I wanted to avoid double posting it, and this post is about safely using insulation, while the other post relates to closing air gaps in the stove.

Refurbishing a Salvo Citation


 
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Post by spiker » Tue. Feb. 23, 2010 11:43 am

I have had the stove going 3 days now and the insulation seems to be doing the job. The stove is responsive, with the ash door open a few minutes, the fire perks up easily. I interpret this to mean that air is not by-passing the grates. I won't know for sure until I let the fire go out and can look more closely, but for now I do not see any signs of deterioration in the insulation. The weather has not been cold this week, and I am running the stove around 300-350. A better test will be in bitter cold weather when I run it in the 400-500 range.

I would say that so long as the insulation is not in direct contact with the fire, there is no problem using it inside a stove. Because I wanted it to cut off air flow, I jammed it into spots, since in its fluffy state it would not stop air very well.
Last edited by spiker on Tue. Feb. 23, 2010 1:45 pm, edited 1 time in total.

 
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Post by Poconoeagle » Tue. Feb. 23, 2010 1:00 pm

I think this waterglass works better and is more cost effective. this 4 oz bottle lasts a long time
when using a cheap acid brush to apply sparingly for rope gaskets.

 
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Post by lowfog01 » Tue. Feb. 23, 2010 1:12 pm

spiker wrote: I jammed it into spots, since in its fluffy state it would not stop air very well.
Just a thought - when we finished our basement the county code inspector made us use a fiber insulation called "rockwool" to form a firebreak and fill a gap in the ceiling joists. It's not as fluffy as the everyday pink stuff and so would block more of the air. It’s not supposed to be able to burn, either. It's also way more expensive but it may hold up better over the long run. Just thought I'd mention it. Lisa

 
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Post by spiker » Tue. Feb. 23, 2010 1:37 pm

Thanks for the suggestions. In this case, the gaps to plug are around 1 in square, so rope gaskets do not seem to be the answer. Also they are irregular in shape and so a malleable material is easier to work with than cutting fire brick or steel to fit.

What is waterglass? It was hard to tell from the image.

I thought about rock wool because it is non flammable, but I have never seen it is stores and since I figured the fiberglass would work, I did not search for it. What suppliers offer rock wool, for future reference?

 
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Post by Poconoeagle » Tue. Feb. 23, 2010 1:47 pm

"Mineral wool, mineral fibres or man-made mineral fibres are fibres made from natural or synthetic minerals or metal oxides. The latter term is generally used to refer solely to synthetic materials including fibreglass, ceramic fibres and rock or stone wool. Industrial applications of mineral wool include thermal insulation, filtration, soundproofing, and "

https://en.wikipedia.org/wiki/Mineral_wool

check with your local plumbing supply house, comercial type...

Lynn Manufacturing in mass sells the clear liquid "waterglass".... its a glue...

http://www.rsifibre.com/
http://www.thomasnet.com/products/insulation-mine ... 408-1.html


 
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Post by lowfog01 » Tue. Feb. 23, 2010 5:52 pm

spiker wrote: What suppliers offer rock wool, for future reference?
We had to go to a contractor's supply house to get ours and then we had to buy the entire bale even though I only needed about a 1/3 of it. As I said it was very expensive especially since we only needed a little of it. Good luck, Lisa

 
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Post by CapeCoaler » Wed. Feb. 24, 2010 8:08 am

Also avalible from Rutland...
**Broken Link(s) Removed**Its old school...
Works great for gaskets...
The only stuff I use...

 
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Post by spiker » Thu. Feb. 25, 2010 9:35 am

I wanted to avoid double posting images to not waste server resources (they are also in another post), but adding these 2 will help see how I am using the insulation. The location is the front left of the stove at the level of the grates. They represent before and after photos. The stove has been very responsive to how much air I allow to enter under the grates and so I believe the insulation is doing the job of reducing air flow that would otherwise by-pass the fire bed.

Attachments

SideGaps.JPG

Air gaps before insulation

.JPG | 19KB | SideGaps.JPG
GapPlugged.JPG

Insulation plugging the gaps

.JPG | 21KB | GapPlugged.JPG

 
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Post by spiker » Fri. Oct. 15, 2010 9:55 am

Wanted to give an update. The fiberglass has worked well, and does not show signs of deterioration. The hottest the stove got was around 700 F one time I left the ash door open accidentally. The stove has been responsive to air intake, so I believe the glass is doing the job I asked of it to force airflow through the grates.

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