Insulated flex liner installation and rock wool

[ruSSrt]

Good afternoon.

I'm working through insulated flex liner installing right now. And have 3 questions.
I have 13x13 opening in clay tile that I dropped down 8" insulated flex liner. It filled the gap pretty well but there are still a little bit of room left. Would I benefit from getting some rock wool and stuffing gaps at the top between SS liner and clay tile, before I put chimney cap on and then also putting some wool at the bottom of the chimney. Maybe filling a smoke chamber or smoke shelve with rock wool to keep heat closer to the living space than going up the flue?
Couple of pictures showing that liner coming down. I removed most of the smoke shelve out so it'll have a straight shot to the stove. And created extra room. Another picture showing appliance connector to the stack conversion piece. This is buck stove rectangular to 8" round adapter. Where would you suggest to attach auber thermocouple sensor? It's supposed to be attached with a screw about 18 inches above the stove. The buck stove adapter is 12 inches and another 6 inches of appliance connector. I was thinking about just putting sensor/thermocouple between adapter and appliance connector. Would that be accurate?
Also do I need to screw adapter and appliance connector together? They hold pretty good and snug fit. So I still need to attach them with screws?
Stove will be put inside the fireplace and I have facia kit that will cover all the gaps to seal it off.
Thank you for your advice.

 

[stoveliker]

I would not bother stuffing rock wool next to the liner.
But I would advise to put a block off plate with rockwool insulation at the bottom of the flue (smoke chamber). Metal with silicone caulk to prevent air leakage to and from the cold chimney bricks.

If you add a thermometer, I'd use a probe (in the flue gases) rather than a surface one.

The other questions I leave to those with more experience

 

[ruSSrt]

I would not bother stuffing rock wool next to the liner.
But I would advise to put a block off plate with rockwool insulation at the bottom of the flue (smoke chamber). Metal with silicone caulk to prevent air leakage to and from the cold chimney bricks.

If you add a thermometer, I'd use a probe (in the flue gases) rather than a surface one.

The other questions I leave to those with more experience

With a block off plates I would have something custom made and it would be very awkward shape unless I make it right at the flue. At which I thought I can just do a poor man's method and put rockwool around to keep heat down.
I see how probe would be more accurate but two things. I didn't want to drill through liner, that's why i wanted to go with thermocouple one. And when I will be sweeping my chimney I would have to be very careful or remove the probe to get a good cleaning there. With thermocouple I don't have to worry about it and just sweep away myself.

 

[stoveliker]

Probe Makes sense.
Thermocouple as high on the liner as possible (as close to 18" as possible). This would make it easier to compare to readings of other folks. No big deal if it's closer, just remember your reading will be higher than the "more standard" 18" off the stove measurement.

Block-off plates are always custom made. Get some metal plate from your hardware store, cut it to size (using cardboard to determine its shape first so no mistakes are made), screw it in the stone with a bead of silicone (no perfect shape needed with silicone), and have some rockwool on top.
Rockwool itself is not preventing air flow... (Hence homes needing air sealing before insulating an attic...)

I read recently there are Alu-faced rockwool plates that one can buy to build insulation - tape the seams and it's air tight (enough) as well.
That also avoids sending a lot of heat thru the brick to the outside world (it's an outside wall, I think from the window).

Insulate the whole box and avoid air going up and you'll get a *lot* more heat out of the thing.
(And, to be sure, rockwool, not fiberglass.)

 

[ruSSrt]

Probe Makes sense.
Thermocouple as high on the liner as possible (as close to 18" as possible). This would make it easier to compare to readings of other folks. No big deal if it's closer, just remember your reading will be higher than the "more standard" 18" off the stove measurement.

Block-off plates are always custom made. Get some metal plate from your hardware store, cut it to size (using cardboard to determine its shape first so no mistakes are made), screw it in the stone with a bead of silicone (no perfect shape needed with silicone), and have some rockwool on top.
Rockwool itself is not preventing air flow... (Hence homes needing air sealing before insulating an attic...)

I read recently there are Alu-faced rockwool plates that one can buy to build insulation - tape the seams and it's air tight (enough) as well.
That also avoids sending a lot of heat thru the brick to the outside world (it's an outside wall, I think from the window).

Insulate the whole box and avoid air going up and you'll get a *lot* more heat out of the thing.
(And, to be sure, rockwool, not fiberglass.)

I didn't even think about cardboard. Thank you. That is a great idea.

 

[stoveliker]

I didn't even think about cardboard. Thank you. That is a great idea.

That's the amateur (my) way for measuring complicated shapes - I can't measure precise enough otherwise

 

[Tonty]

Not just your way. 😁I used to lay floor covering, and while we would usually lay vinyl in loose and cut to fit, every once in a while on a complicated lay we would use pattern paper and actually build a pattern, lay the pattern on, and cut the vinyl before install. Some floor covering fellows do it more often than not.

 

[Solarguy3500]

I read recently there are Alu-faced rockwool plates that one can buy to build insulation - tape the seams and it's air tight (enough) as well.

Lots of really good info here. Cardboard templates are your friend when making your blockoff plate.

I used the foil faced Roxul mentioned above when I installed my insert. It worked really well. It is a semi rigid board that has binders in it to make it rigid, while also controlling fibers from getting airborn and getting into the room. If you tape the seams with a good quality foil tape such as the type that is used for taping an insulation kit on a liner, it will further seal in fibers and keep warm air from escaping through the gaps between pieces. Here's how mine came out:




I have an insert and rather than install the faceplate on it, I opted to leave it off to get more heat out into the room. I made a sheet metal trim kit and painted it with black stove paint to cover the foil faced Roxul and make it look a little nicer, but if the Roxul won't be visible in your situation, or you don't mind the look of it you can skip that step.




@mellow has a really good thread about insulating the fireplace and installing a blockoff plate. It's long but well worth the read as there is a ton of great info in it.

Edit: Here's the link:

Finally got around to insulating my fireplace

Used Roxul R-15.

www.hearth.com

 

[ruSSrt]

That looks amazing! I'm definitely looking in to it.
Thank you for posting that

 

[mellow]

All this work and you will be sending a good portion of the heat potential up and out the chimney

I would check out this old thread on retrofitting a buck to make it burn cleaner:

I Modified My Buck Stove 27000 Insert for Secondary Burn. Now Have Questions

We have an old 27000 model Buck Stove insert mounted in the fireplace opening. It has been there for years and was probably built in the early 80's. After reading on here for the last couple of years, I decided to try something with the old stove. I know this isn't an EPA model and isn't very...

www.hearth.com

 

[mellow]

Another old thread on adding secondary:

Silent Flame Retrofit - Secondary Air, Firebrick, etc..

Hey guys... Ive really been tossing around the idea of baffling my old stove and adding a secondary burn system.. but the question is will a secondary burner function on a stove that isn't air tight? Where the doors on my stove close, there is approximately a 1/4" gap between the doors that...

www.hearth.com

 

[ruSSrt]

Another old thread on adding secondary:

Silent Flame Retrofit - Secondary Air, Firebrick, etc..

Hey guys... Ive really been tossing around the idea of baffling my old stove and adding a secondary burn system.. but the question is will a secondary burner function on a stove that isn't air tight? Where the doors on my stove close, there is approximately a 1/4" gap between the doors that...

www.hearth.com

Thank you. Main reason why I started to install the liner and do all the work is because I was running my stove with damper shut pretty much 90% of the time. Which in turn made a huge mess in my fireplace smoke box and clay lined chimney. With flex liner I will be running it the same, but this way at least I can clean it in 15-20 minutes every other month myself.

 

[bholler]

Thank you. Main reason why I started to install the liner and do all the work is because I was running my stove with damper shut pretty much 90% of the time. Which in turn made a huge mess in my fireplace smoke box and clay lined chimney. With flex liner I will be running it the same, but this way at least I can clean it in 15-20 minutes every other month myself.

What moisture content is your wood at?

If that's the case this big old stove is simply to big for your home as most were

 

[ruSSrt]

What moisture content is your wood at?

If that's the case this big old stove is simply to big for your home as most were

I was burning poorly seasoned wood. It was close to 20% on a freshly split inside.

I have 2500 sq ft single story home. My big buck 28000 had some intermittent fan issues. It would run and don't run, sometimes run continuously. Now I got new fan with new thermal disks. Pretty much changed all the changeable parts in it. I put box fan at the door to push cold air in to that room so hot air flows around the house. It worked really good.

 

[ruSSrt]

Update after all the work.

I have not put in block off plates this season. Plan for next heating season. But I added brick in to the stove. It made a night and day difference.
I added at least 3-4 hours of burn time to it. I also kept the fireplace open, did not install the face kit and room heats up much quicker.
Upgrades were totally worth it.