Roxul in damper

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
  • Hope everyone has a wonderful and warm Thanksgiving!
  • Super Cedar firestarters 30% discount Use code Hearth2024 Click here

Ctwoodtick

Minister of Fire
Jun 5, 2015
2,229
Southeast CT
so, when I had my insert installed a while back, my installer had room to put liner through damper so damper frame not removed. He stuffed roxul in the damper space to reduce heat loss. Had I known at the time about benefits of block off plates, I’d have gone in that direction.
I notice I get some small amount of roxul that get into where the insert blows out warm air into room. The shroud of insert has some small spaces around flue collar where Roxul could fall into. I’d like to eliminate this from happening. Is there a retrofit blockoff plate I can put up without removing damper. I’d like to keep the insulation benefit of the roxul and imagine if it’s above a blockoff plate, no roxul would fall down.
Also, how much benefit is there with roxul in damper area, without a blockoff plate?
 
I made my block off plate from thin gauge sheet metal. Put the roxul up around the liner above the block off plate. Roxul alone will not completely stop the flow of hot air up the chimney on the outside of the liner.
 
You don’t need to remove or alter the damper. A block of plate is just a piece of sheet metal somewhere below that turns the fireplace more into an alcove. Just cut it to fit around the liner and screw it into the mortar between the bricks with Roxul on top.

There’s tons of threads on here about block off plates to give you ideas. I did mine after the install without disconnecting the liner.

[Hearth.com] Roxul in damper



Sent from my iPhone using Tapatalk
 
You can make a block off plate in two overlapping pieces (a left side and a right side which both have sort of a semi-circle that overlaps around the liner), which can be easier to get on. I made mine with 22 gauge steel that they sell in sheets at Lowes, some inexpensive sheet metal snips, and some files and metal sandpaper to smooth out the very sharp edges. Wear good gloves as that sheet metal will cut right through you easily! Also, if you use regular steel, might not be a bad idea to paint with high temp paint, as it’s very susceptible to oxidation.
 
You don’t need to remove or alter the damper. A block of plate is just a piece of sheet metal somewhere below that turns the fireplace more into an alcove. Just cut it to fit around the liner and screw it into the mortar between the bricks with Roxul on top.

There’s tons of threads on here about block off plates to give you ideas. I did mine after the install without disconnecting the liner.

View attachment 234528

Sent from my iPhone using Tapatalk


What's the wire for?
 
Most Roxul fibers and dust are microscopic and will inevitably shed with any disturbance or even convective air currents so I too feel it's wise to seal it up. I had Roxul all around my insert and pulled it all out everywhere except above the block off. The insert is a bit less efficient (although the Montpelier actually does have kaowool insulation on the bottom and sides, so minimal difference) but after reading all the studies on breathing Roxul fibers I'm not convinced it is safe. It's not asbestos level but could be dangerous and I don't want to expose my family to the fibers for the countless hours the insert will be burning and blowers blowing.

I have a weird round to oval piece coming off my stove so the hole needed to be a weird shape. Instead of sheet metal I used 321 stainless steel foil, cut it to shape and used furnace cement to glue it to the masonry. Expensive stuff but I have found it useful for other stove related things (like stuffing some in my secondary tubes as they were bringing way too much air into the firebox even with the primary air closed...aluminum foil would melt at those temps)
 
Most Roxul fibers and dust are microscopic and will inevitably shed with any disturbance or even convective air currents so I too feel it's wise to seal it up. I had Roxul all around my insert and pulled it all out everywhere except above the block off. The insert is a bit less efficient (although the Montpelier actually does have kaowool insulation on the bottom and sides, so minimal difference) but after reading all the studies on breathing Roxul fibers I'm not convinced it is safe. It's not asbestos level but could be dangerous and I don't want to expose my family to the fibers for the countless hours the insert will be burning and blowers blowing.

I have a weird round to oval piece coming off my stove so the hole needed to be a weird shape. Instead of sheet metal I used 321 stainless steel foil, cut it to shape and used furnace cement to glue it to the masonry. Expensive stuff but I have found it useful for other stove related things (like stuffing some in my secondary tubes as they were bringing way too much air into the firebox even with the primary air closed...aluminum foil would melt at those temps)
Thanks,
Most Roxul fibers and dust are microscopic and will inevitably shed with any disturbance or even convective air currents so I too feel it's wise to seal it up. I had Roxul all around my insert and pulled it all out everywhere except above the block off. The insert is a bit less efficient (although the Montpelier actually does have kaowool insulation on the bottom and sides, so minimal difference) but after reading all the studies on breathing Roxul fibers I'm not convinced it is safe. It's not asbestos level but could be dangerous and I don't want to expose my family to the fibers for the countless hours the insert will be burning and blowers blowing.

I have a weird round to oval piece coming off my stove so the hole needed to be a weird shape. Instead of sheet metal I used 321 stainless steel foil, cut it to shape and used furnace cement to glue it to the masonry. Expensive stuff but I have found it useful for other stove related things (like stuffing some in my secondary tubes as they were bringing way too much air into the firebox even with the primary air closed...aluminum foil would melt at those temps)
That you know of, is there any documented health problem from roxul, aside from the respiratory irritation that usually is listed?
 
An increase in fibrosis (scarring of the lungs) with long-term exposure. Most other lung related ailments showed a slight increase with those exposed over long periods. Supposedly the body can clear these fibers out of the lungs - only like 10% of fibers remained after 90 days, but I'm not sure how long term constant exposure would affect that.

It's potentially a carcinogen although the evidence there is weak. But asbestos was once found to be safe, too. Like I said all signs point to it being a lot safer than asbestos but I felt that I couldntc relax or enjoy my fires knowing I may be exposing my 16 month old son to something that may be dangerous and where symptoms wouldn't show for 20 or 30 years.

It's a risk benefit analysis and as we don't heat with wood exclusively I just couldnt justify it. I didn't have room in the back or sides of the insert to properly enapsulate the Roxul so I just pulled it. Maybe someday I will revisit insulating the firebox with an inch of encapsulated micore, but for now I'm ok with the losses of having it uninsulated. the insert itself doesn't perform much differently. In fact, I think having the Roxul right up against it was a bad idea as it was harder to cool the unit if it was heading towards overfire tesrritory
 
An increase in fibrosis (scarring of the lungs) with long-term exposure. Most other lung related ailments showed a slight increase with those exposed over long periods. Supposedly the body can clear these fibers out of the lungs - only like 10% of fibers remained after 90 days, but I'm not sure how long term constant exposure would affect that.

It's potentially a carcinogen although the evidence there is weak. But asbestos was once found to be safe, too. Like I said all signs point to it being a lot safer than asbestos but I felt that I couldntc relax or enjoy my fires knowing I may be exposing my 16 month old son to something that may be dangerous and where symptoms wouldn't show for 20 or 30 years.
Duly noted, I’ll make this thing safe one way or other ASAP, thsnks
 
An increase in fibrosis (scarring of the lungs) with long-term exposure. Most other lung related ailments showed a slight increase with those exposed over long periods. Supposedly the body can clear these fibers out of the lungs - only like 10% of fibers remained after 90 days, but I'm not sure how long term constant exposure would affect that.

It's potentially a carcinogen although the evidence there is weak. But asbestos was once found to be safe, too. Like I said all signs point to it being a lot safer than asbestos but I felt that I couldntc relax or enjoy my fires knowing I may be exposing my 16 month old son to something that may be dangerous and where symptoms wouldn't show for 20 or 30 years.

It's a risk benefit analysis and as we don't heat with wood exclusively I just couldnt justify it. I didn't have room in the back or sides of the insert to properly enapsulate the Roxul so I just pulled it. Maybe someday I will revisit insulating the firebox with an inch of encapsulated micore, but for now I'm ok with the losses of having it uninsulated. the insert itself doesn't perform much differently. In fact, I think having the Roxul right up against it was a bad idea as it was harder to cool the unit if it was heading towards overfire tesrritory
If you are worried about it, taking it out is the right thing to do. Doesn't matter whether it actually causes physical harm, it's doing a different kind of damage by causing the worry. Hopefully in time, it's not discovered to be bad like asbestos, but if it is, you don't have to worry about it.
 
If you are worried about it, taking it out is the right thing to do. Doesn't matter whether it actually causes physical harm, it's doing a different kind of damage by causing the worry. Hopefully in time, it's not discovered to be bad like asbestos, but if it is, you don't have to worry about it.
That's exactly where I was at with it mentally.

I couldn't really get it out of the damper area without pulling the liner (difficult with a rigid liner). I have some stuffed up at the top too and some inevitably fell alongisde the liner's length. So I figured it best to just encapsulate with a blockoff plate. It's not 100% perfectly sealed but say 99%, and I'm comfortable with that.
 
What's the wire for?

That’s my Auber thermometer (digital read out and hi temp alarm). Beats the old magnetic thermometer and pointing the Ir gun into the air outlet.

[Hearth.com] Roxul in damper


In the pic I had it attached to the collar. I have a thin wall liner so I can’t screw it it directly into it. That location was ok, but I found it registered a little cooler and was slower to respond than my old way of pointing the IR gun at the collar / stove connection. Now I have it in between the liner and the adapter a few inches up. It’s been working really well there.


Sent from my iPhone using Tapatalk
 
  • Like
Reactions: redktmrider