Hot metal smell - Roxul?

[Remdo]

I haven’t noticed any smell since the first time that the Roxul was heated. It was quite noticeable that first time, and lasted a few hours. Since that was in the fall I opened a few windows to air the smell out. Next day there was no problem. My insert has burned at least a full cord of wood since the install, and no troubles. Hope this is helpful.

Yes it does, A lot! thank you for your response. I wasn't sure how long this smell will linger. Like you said it was strong in beginning for the first few hours then slowly dissipated. I have definitely noticed an increase in the heat output by insulating it from the top the back and the sides. I just hope this doesn't jeopardize the safety of the unit in any way. Not only the unit but our safety as well. I've been doing a Night Watch in front of the fireplace making sure nothing is out of the order. Every little click and bang wakes me up. do you think that by insulating it from all sides we are overheating the unit in anyway? The chimney and the flue are definitely cooler to the touch. Which means that roxul is doing its job by insulating the heat from escaping. But if the unit can't radiate anticipate some of the heat externally isn't that bad for the unit? I don't know, kind of new to this. I just thought I wanted to increase the heat output, because in my opinion it wasn't the greatest for the amount of wood I was burning. Now that it seems that the blower is pushing out hotter air out of the vent, I find myself asking more questions than before. Is it safe, will this cause the unit to over fire? And how would I know? Once again thanks for any response.

R

 

[Bushels20]

Hey guys, it is February 1st ,2019..so a few months after you have opened this thread. Could anybody tell me what they have experienced in the last few months as far as roxul off-gassing? today I have done exactly the same thing you have described to my wood burning insert. I felt it was losing too much heat so I insulated both sides the back and double or triple layer on top. As soon as I lit the fire I smelt the odor you were describing! I have a cranking on high for the last couple hours hoping that it will eventually off gas, will it? Has it for you? Please let me know it has! Because it is throwing back a lot more heat back into the house. I I would like to keep this configuration without the odor and potentially some health risks. Any response would be greatly appreciated

R

When I insulated in early October and lit my first fire, the smell lasted for a day or so. After that, back to normal.

 

[danham]

Just to add another data point, I added Roxul as a block-off and also behind and to the sides of the insert. This was long after initial burn-in of the stove and I got no new smells. Then we moved away for four years and when we returned a few weeks ago and had our first fire, we got a little of that "first furnace run/burning dust" smell, but it went away after the second fire. I doubt it was the Roxul.

-dan

 

[Ben Stark]

Yes it does, A lot! thank you for your response. I wasn't sure how long this smell will linger. Like you said it was strong in beginning for the first few hours then slowly dissipated. I have definitely noticed an increase in the heat output by insulating it from the top the back and the sides. I just hope this doesn't jeopardize the safety of the unit in any way. Not only the unit but our safety as well. I've been doing a Night Watch in front of the fireplace making sure nothing is out of the order. Every little click and bang wakes me up. do you think that by insulating it from all sides we are overheating the unit in anyway? The chimney and the flue are definitely cooler to the touch. Which means that roxul is doing its job by insulating the heat from escaping. But if the unit can't radiate anticipate some of the heat externally isn't that bad for the unit? I don't know, kind of new to this. I just thought I wanted to increase the heat output, because in my opinion it wasn't the greatest for the amount of wood I was burning. Now that it seems that the blower is pushing out hotter air out of the vent, I find myself asking more questions than before. Is it safe, will this cause the unit to over fire? And how would I know? Once again thanks for any response.

R

My insert is small, and I placed the Roxul tight to the fireplace masonry, leaving a gap of a couple inches between the exterior of the insert and the rock wool. It is also a few inches above the top of the insert. My goal was to slow down the loss of heat through the old fireplace. So the Roxul is not actually pressed right to the insert.

If any part of the insert starts to glow cherrie red, like the stove top, door frame, sides, etc. This would be a sure sign of over firing the stove.

 

[SculptureOfSound]

I tore mine out. I had it in the sides and back pressed tight to the insert. I had the smell for a bit but it could have been other things...paint or oil burning off the new liner or the Roxul. Had a few real hot burns too, maybe overfires I couldn't stay and check as I took my g/f and our one year old out of the house to escape the smell. Too much really dry pine got the unit real hot.

I do think the Roxul was the source of my smells but at the time I didn't have a proper blockoff plate, just Roxul tucked up there and Roxul dust and fibers had fallen in the top of my insert during the install. My insert has a portion in the.middle where the actual stove top is exposed so Roxul fibers were seeing temps of 650-700 degrees. probably wouldnt have happened with a more normal insert that has the convective jacket covering the whole top.

Anyhow I ripped it out due to the smell but also due to research on the effects of the fibers in our lungs. The research is limited but these fibers due seem to cause some long term damage with high exposure. Research shows most fibers are expelled by the body within 90 days but they were only looking at the longer lengths. No idea what happens with the super tiny microscopically long fibers. It may not look the Roxul is shedding fibers because most are so tiny, but if you say, take your phone light and shine it near the Roxul and then tap it, you will see clouds of tiny dust-like fibers escaping.

I figured pressed tight against the insert and above it with no blockoff these fibers would find a way into the blower air path and took out all the roxul in the firebox and made a proper blockoff plate above the unit. Still have Roxul above the blockoff and no smell now.

 

[Phileo]

It is the Roxul/mineral wool that is the culprit! I had a wood stove insert installed and Roxul was stuffed between the new uninsulated flue and the existing masonry flue. For a year everytime we lit the stove about 30 minutes into the burn a strong chemical odor would fill the room. This would persist every time and we did over a dozen fires with some for extended burns. We tried everything, and then eventually tried heating a piece of the Roxul on our kitchen stove--same smell. After we removed all of the Roxul, vacuumed, and wiped the Roxul dust off the stove the smell went away. I don't know what brand of mineral wool was used, but when in contact with very high heat it emits a smell. It might be fine if not directly in contact with an uninsulated flue, but I wouldn't use it and was shocked based on it being frequently marketed with a blowtorch trying to ignite it!

 

[John B]

I am using Roxul in place of a block off, and no issues with smell or dust.

I also did a test with some insense and I dont see any air pulling up through it, rather there seems to be a nice convection out of the front of the hearth and up into the room. I am not convinced I even need a block off at this point given how well the heat transfer is happening to the room.

 

[Solarguy3500]

Another option is to use the foil faced Roxul which comes in different thicknesses from 1" to 4" and fully tape the seams with foil tape, like the kind used on liner insulation.

https://www.grainger.com/product/ROXUL-2-in-x-48-in-x-24-in-Mineral-19NE83

Another member on here @unimog1300 did the back and sides of his fireplace with it and after reading his posts, I decided to go this route when I install my insert. The foil face will keep any fibers contained behind the foil, but as an extra layer of protection I plan to also add a series of sheet metal heat shields over the foil faced roxul sealed with a high temp sealant when I install my insert. I'll post an update when it's done, but that probably won't be until next heating season, as I discovered that my chimney needs some work before installing the liner and insert.