Roxul help

[KennyK]

Hearth friends,

I'm trying to get more heat from my stove (Jotul F100 installed in fireplace opening with back legs in firebox) into the house and I just picked up some roxul and have three questions:

1) I bought the roxul Comfortbatt (pic attached) - is this fine? They also had the roxul safe n sound at Home Depot, but I think the only difference is that is if you also want sound proofing and it's more expensive.

2) The people who installed the liner and stove put in a block off plate at the damper with a thin piece of insulation above it. They didn't seal their blockoff plate so I can get it off and was thinking to stuff as much roxul in the smoke chamber, above the block off plate, as possible. Is this a good plan? I will then put back the blockoff plate back and seal with high temp silicone.

3) A lot of heat is getting trapped in the fireplace firebox behind the stove (and perhaps getting absorbed into masonry). I am thinking to stuff the back of the firebox with the roxul from top to bottom and right up to the T for the liner, then putting up a steel sheet (kind of like another block off plate but in the fireplace firebox from floor to lintel). I'd still leave six inches of distance between the back of the stove and the steel sheet, which is the minimum clearance to protected surfaces for the stove. I've also attached a pic of my stove setup in case that helps. Thoughts?

Any input on any of this and/or other ideas is welcome!

 

[redktmrider]

I bought the roxul Comfortbatt

That is what I have installed between my the outer jacket of my insert and masonry chimney. It's been there for about 3 years and seems to holding up fine. I think this is one of those situations where an insert might have an advantage over the freestanding stove.
Ashful had Jotuls in his masonary chimneys, maybe he knows more about it.

 

[begreen]

Should be ok, even if the metal was within an inch of the flue. It's all non-combustible. Be careful when stuffing above the blockoff plate so that the liner is not dented (if thin wall).

 

[Easy Livin’ 3000]

Hearth friends,

I'm trying to get more heat from my stove (Jotul F100 installed in fireplace opening with back legs in firebox) into the house and I just picked up some roxul and have three questions:

1) I bought the roxul Comfortbatt (pic attached) - is this fine? They also had the roxul safe n sound at Home Depot, but I think the only difference is that is if you also want sound proofing and it's more expensive.

2) The people who installed the liner and stove put in a block off plate at the damper with a thin piece of insulation above it. They didn't seal their blockoff plate so I can get it off and was thinking to stuff as much roxul in the smoke chamber, above the block off plate, as possible. Is this a good plan? I will then put back the blockoff plate back and seal with high temp silicone.

3) A lot of heat is getting trapped in the fireplace firebox behind the stove (and perhaps getting absorbed into masonry). I am thinking to stuff the back of the firebox with the roxul from top to bottom and right up to the T for the liner, then putting up a steel sheet (kind of like another block off plate but in the fireplace firebox from floor to lintel). I'd still leave six inches of distance between the back of the stove and the steel sheet, which is the minimum clearance to protected surfaces for the stove. I've also attached a pic of my stove setup in case that helps. Thoughts?

Any input on any of this and/or other ideas is welcome!

View attachment 221831 View attachment 221830

Sounds like you are making progress. I second begreen, no need to leave the 6". Just an inch would leave less room for heat to collect where it's not useful.

No need to fill the entire space behind the vertical block off plate behind the stove. Just adhere one thickness of the Roxul to the steel plate. You already have my advice on how to accomplish that.

I doubt it would make too much difference either way. A fan will help.

Regarding the Roxul, I figured that the additional density of the safe and sound was better in this application, but I highly doubt you'll notice the difference. Particularly if you are tearing and stuffing.

How much cheaper was the comfort batt?

 

[Jan Pijpelink]

I installed an insert yesterday and made a new block off plate, the first one I made for the previous stove was crap. I have Roxul gently stuffed around the liner and in the smoke chamber and it makes a huge difference.

 

[jetsam]

The regular Roxul is better thermal insulation. Safe'n'sound is better acoustic insulation, but they don't even publish R values for it last time I checked.

I would say that the stuff you got is slightly better for that application, but it really doesn't matter too much.

 

[KennyK]

I installed an insert yesterday and made a new block off plate, the first one I made for the previous stove was crap. I have Roxul gently stuffed around the liner and in the smoke chamber and it makes a huge difference.

Helpful to know, thanks! I think it's going to be a bit challenging as the stove is in place and I don't think I can get the current plate all the way off without a major operation, but I'm going to do the best I can for now and can always revisit again later.

Regarding the Roxul, I figured that the additional density of the safe and sound was better in this application, but I highly doubt you'll notice the difference. Particularly if you are tearing and stuffing.

How much cheaper was the comfort batt?

A giant bag of the safe n sound was about $48 and the comfort batt was $43, but the package was open so they gave me $10 off that price!

 

[Easy Livin’ 3000]

Helpful to know, thanks! I think it's going to be a bit challenging as the stove is in place and I don't think I can get the current plate all the way off without a major operation, but I'm going to do the best I can for now and can always revisit again later.



A giant bag of the safe n sound was about $48 and the comfort batt was $43, but the package was open so they gave me $10 off that price!

I'd have definitely gone with the comfort batt like you did. Good sale you found. And, according to Jetsam, it's better r value, too.

 

[jetsam]

Same material, different densities. More air space is better for thermal insulation; less is better for acoustic insulation.

 

[Easy Livin’ 3000]

Same material, different densities. More air space is better for thermal insulation; less is better for acoustic insulation.

Make sense. Most of mine was crammed up into the smoke shelf and chimney. Probably not as fluffy as it started.

 

[jetsam]

Make sense. Most of mine was crammed up into the smoke shelf and chimney. Probably not as fluffy as it started.

Yeah, if you buy R30 and stuff it into a 2x4 wall, it's significantly worse insulation than the R13 you should have used. Same principle.

 

[KennyK]

Just packed the smoke chamber as much as I could and wherever else I could get to above the block off plate (with the help of a few broom handles!). Man was that a royal pain in the rear! Would certainly have been easier before the stove and blockoff plate were in place, and I may have been able to get more roxul up there, but I got just shy of two and a half batts up there, which is more that I would have thought and I'm feeling pretty good about it.

Same material, different densities. More air space is better for thermal insulation; less is better for acoustic insulation.

Jetsam, as much as I could without being too rough on the liner, I packed it pretty densely. Should I have not packed it dense? I'd really prefer not to mess with it anymore as it's a pretty nasty job (even wearing a hepa filter mask, I'm still caughing!), but if I am going to fix anything, now's the time. Any cause for concern? Any advice?

Should be ok, even if the metal was within an inch of the flue. It's all non-combustible. Be careful when stuffing above the blockoff plate so that the liner is not dented (if thin wall).

Good advise about being careful with the liner Begreen! I don't believe my liner is thin wall - it's a best flex crossover, which I'm told is heavier than a thin walled but a bit thinner than a heavy walled - but either way, I heard your comment in my mind as I was working and was careful not to be too rough!

One other thing: the company that did the install and put in the blockoff plate put a thin piece of some white insulation above the blockoff plate. I left that there, but I'm wondering if anyone knows anything about some completely white insulation and if that sounds normal. It looks very different than the roxul and I could remove it easily if necessary- it's only about an inch thick. Thoughts?

Now, on to the sheet metal behind the stove!

Oh, and here's a before and after pic! (actually got even more roxul after the after pic, but took this while there was still room to get my camera up there!). Note that my liner is insulated, but they cut a bit of the insulation off above the damper to get it through the opening, which you can see in the first pic. Now it's got insulation all around it with the roxul up until it passes through the blockoff plate.

 

[begreen]

The white stuff is kaowool. It's a ceramic insulation and quite appropriate.

 

[Easy Livin’ 3000]

Just packed the smoke chamber as much as I could and wherever else I could get to above the block off plate (with the help of a few broom handles!). Man was that a royal pain in the rear! Would certainly have been easier before the stove and blockoff plate were in place, and I may have been able to get more roxul up there, but I got just shy of two and a half batts up there, which is more that I would have thought and I'm feeling pretty good about it.



Jetsam, as much as I could without being too rough on the liner, I packed it pretty densely. Should I have not packed it dense? I'd really prefer not to mess with it anymore as it's a pretty nasty job (even wearing a hepa filter mask, I'm still caughing!), but if I am going to fix anything, now's the time. Any cause for concern? Any advice?



Good advise about being careful with the liner Begreen! I don't believe my liner is thin wall - it's a best flex crossover, which I'm told is heavier than a thin walled but a bit thinner than a heavy walled - but either way, I heard your comment in my mind as I was working and was careful not to be too rough!

One other thing: the company that did the install and put in the blockoff plate put a thin piece of some white insulation above the blockoff plate. I left that there, but I'm wondering if anyone knows anything about some completely white insulation and if that sounds normal. It looks very different than the roxul and I could remove it easily if necessary- it's only about an inch thick. Thoughts?

Now, on to the sheet metal behind the stove!

Oh, and here's a before and after pic! (actually got even more roxul after the after pic, but took this while there was still room to get my camera up there!). Note that my liner is insulated, but they cut a bit of the insulation off above the damper to get it through the opening, which you can see in the first pic. Now it's got insulation all around it with the roxul up until it passes through the blockoff plate.

View attachment 221899

View attachment 221900

Good progress. I'd say don't mess with the insulation up the chimney any more, you did a good job. You can focus on the sheet, I think that's where you'll be getting the most bang for your buck keeping the heat in the room

 

[jetsam]

Jetsam, as much as I could without being too rough on the liner, I packed it pretty densely. Should I have not packed it dense? I'd really prefer not to mess with it anymore as it's a pretty nasty job (even wearing a hepa filter mask, I'm still caughing!), but if I am going to fix anything, now's the time. Any cause for concern? Any advice?

Nope. Mashed up like that it's worse thermal insulation. It would probably be better if you pulled out enough that it could expand, but I doubt you'll notice the difference. I'd leave it be- just make sure your blockoff plate and liner are still ok.

 

[Easy Livin’ 3000]

Nope. Mashed up like that it's worse thermal insulation. It would probably be better if you pulled out enough that it could expand, but I doubt you'll notice the difference. I'd leave it be- just make sure your blockoff plate and liner are still ok.

I was thinking, once that big insulated vertical steel block off plate is in behind the stove, the stuff around the chimney will be less important.

 

[KennyK]

Done! (For now in any case!). Made two steel plates with cutouts that overlap, put roxul behind the plate (just wedged it in the fireplace firebox, so no need to adhere to plate), and put the plates in. Fits well. Going to test it, then I can paint and seal if I don't need any adjustments. Out to a well deserved meal with the fam, and then home to heat it up! Will report more to follow...

 

[KennyK]

Oh, and one more thing, I've got just about three inches between stove and plate - does that look good?

 

[Easy Livin’ 3000]

Oh, and one more thing, I've got just about three inches between stove and plate - does that look good?

View attachment 221927

Looks great. And you might be one of the only ones to use the entire package of Roxul when using it to block off your chimney. Might as well!

I expect that you'll have a much warmer experience going forward.

Well done, and thanks for sharing. Please report back on how it all works for you.

 

[Jan Pijpelink]

Oh, and one more thing, I've got just about three inches between stove and plate - does that look good?

View attachment 221927

I might do the same thing.

 

[Easy Livin’ 3000]

I might do the same thing.

You should. We'd like to read about it. Posts like this are informative and entertaining, and inspiring, apparently!

 

[KennyK]

Ok, so here's the update (and any more advice is welcome!). It works However...

I definitely got more heat into the room. It was 37 outside last night and I got the stove room up to a 74, which I had done before but on a warmer day, and last night it held that temp more consistently and kept the adjacent room warmer. I also got a record burn time (perhaps all-time record for the Jotul F100). I got a good fire going and then filled it sometime between 10 and 11pm, once I got a good fire going again, I closed the damper down almost all the way. This morning at 7:30am the stove still had some coals! The stove was at around 200 degrees and the stove room was around 66/67. Upstairs was at 64. Keep in mind, that's about 2000 square feet of a relatively drafty house! Not the coldest night, but not bad, especially for this little stove. I also got the stove to a bit above 600 for the first time, but that could be other factors like the wood and how well I had it filled - I'm still new at this!

Now, here's the problem (and where some advise is welcome). Above the stove got much hotter than before. I don't have a temp gun (getting one this week), but judging by touch, the heat shield was significantly hotter, and the marble surround above the stove (but not on the sides) was very hot to touch and had me quite nervous (I had trouble going to sleep!). The wood mantel was warmer, but didn't strike me as at all too warm for concern, except for that it's touching the marble (see pic) and I worry about the gradual heating up over time and wondered what becomes unsafe. My fingers are good at handling heat, and I could only touch the part of the marble closest to the stove for a few seconds before needing to move off it - what is too hot?

Here are the options I am thinking about -

1) Scrap the idea of the blockoff plate behind the stove altogether and go back to the open fireplace firebox. A bit of a bummer after a lot of work, but safety is first. Hopefully things will still be a bit warmer with the roxul in the smoke chamber above the lintel level blockoff plate.

2) Keep the blockoff plate behind the stove but move it back two to three more inches to give me five to six inches behind the stove (manual says 5" minimum to protected surfaces).

3) My heat shield is attached to the lintel and it is virtually touching the marble. It is attached with magnets and I can easily lower this by an inch by putting some more magnets, which would give me a inch of airspace between heat shield and marble and I would assume lower the temp of the marble. (I may have to move my ecofan forward an inch or so to accommodate if I do this).

4) A combination of some of the above.

Also, the marble above the ecofan was significantly cooler (though still quite hot), so I just ordered one more of those. I also think this ecofan is doing a good job moving heat off stove and into the room, so a second one will be welcome. Not sure how it would compare to a blower, but seems to have pretty CFM airflow according to the stats the company says (280 to 360 CFM). Here's a link: https://www.amazon.com/dp/B0762PR6XT/?tag=hearthamazon-20

Thanks for the continued advice!

 

[Easy Livin’ 3000]

Ok, so here's the update (and any more advice is welcome!). It works However...

I definitely got more heat into the room. It was 37 outside last night and I got the stove room up to a 74, which I had done before but on a warmer day, and last night it held that temp more consistently and kept the adjacent room warmer. I also got a record burn time (perhaps all-time record for the Jotul F100). I got a good fire going and then filled it sometime between 10 and 11pm, once I got a good fire going again, I closed the damper down almost all the way. This morning at 7:30am the stove still had some coals! The stove was at around 200 degrees and the stove room was around 66/67. Upstairs was at 64. Keep in mind, that's about 2000 square feet of a relatively drafty house! Not the coldest night, but not bad, especially for this little stove. I also got the stove to a bit above 600 for the first time, but that could be other factors like the wood and how well I had it filled - I'm still new at this!

Now, here's the problem (and where some advise is welcome). Above the stove got much hotter than before. I don't have a temp gun (getting one this week), but judging by touch, the heat shield was significantly hotter, and the marble surround above the stove (but not on the sides) was very hot to touch and had me quite nervous (I had trouble going to sleep!). The wood mantel was warmer, but didn't strike me as at all too warm for concern, except for that it's touching the marble (see pic) and I worry about the gradual heating up over time and wondered what becomes unsafe. My fingers are good at handling heat, and I could only touch the part of the marble closest to the stove for a few seconds before needing to move off it - what is too hot?

Here are the options I am thinking about -

1) Scrap the idea of the blockoff plate behind the stove altogether and go back to the open fireplace firebox. A bit of a bummer after a lot of work, but safety is first. Hopefully things will still be a bit warmer with the roxul in the smoke chamber above the lintel level blockoff plate.

2) Keep the blockoff plate behind the stove but move it back two to three more inches to give me five to six inches behind the stove (manual says 5" minimum to protected surfaces).

3) My heat shield is attached to the lintel and it is virtually touching the marble. It is attached with magnets and I can easily lower this by an inch by putting some more magnets, which would give me a inch of airspace between heat shield and marble and I would assume lower the temp of the marble. (I may have to move my ecofan forward an inch or so to accommodate if I do this).

4) A combination of some of the above.

Also, the marble above the ecofan was significantly cooler (though still quite hot), so I just ordered one more of those. I also think this ecofan is doing a good job moving heat off stove and into the room, so a second one will be welcome. Not sure how it would compare to a blower, but seems to have pretty CFM airflow according to the stats the company says (280 to 360 CFM). Here's a link: https://www.amazon.com/dp/B0762PR6XT/?tag=hearthamazon-20

Thanks for the continued advice!

View attachment 221967

Two ideas:

First, a blower or fan. Not another ecofan, they are more expensive novelty than serious air mover.

Second, perhaps the vertical block off plate could be more diagonal. What I mean here is, angle it with more space at the bottom, and have the top terminate where your heat shield begins, assuming you can still clear the stove with an inch or so. Eliminate the horizontal heat trap immediately behind the stove, and hopefully a rising convection current will roll out of the space and into the room.

Both ideas will help your situation.

Like your idea to add magnets to increase the spacing.

 

[begreen]

Oh, and one more thing, I've got just about three inches between stove and plate - does that look good?

View attachment 221927

Yes, as noted early it could be 1/2" and it'd be fine.

 

[KennyK]

Yes, as noted early it could be 1/2" and it'd be fine.

Begreen, I don't doubt your expertise, but it was a little too close for comfort for me. This could be because the back of my stove is right under the fireplace surround, which isn't very tall (30 inches and stove is 22.5") and the marble was getting very hot. I could be wrong about this, but I think that with the metal plate so close to the back of the stove, it was extra hot right in that area. I moved the plate back a few inches more so I now have about 5 or 6 inches from the back of the stove, which is still far less space for hot air to collect than with the open fireplace firebox, but gives the hot air a little more space to disperse (at least according to my amateur scientific theory!). Out of curiosity, however, if the stove manual says that it should have 5 inches clearance to a rear protected surface, why do you feel it's okay to have less? Is a block off plate behind the stove not what they would refer to as a rear surface?