Wood stove rookie--questions on damper seal and insulation

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RamMasterFlash

New Member
Sep 13, 2022
11
Connecticut
Hi all, I am just finalizing the installation of my new Ashley Hearth Fireplace Insert. A bit of background: I have an old stone fireplace with a 20 foot chimney chase. the chase is lined with clay, but am unsure of the condition of the clay. I installed a 20 foot flexible steel liner ( flexible really seems like a poor descriptor!) and insulated the first 16 feet of the liner (from the stove up) with a 1 inch thick insulation blanket from Rockford Chimney Supply. I am now trying to seal off the throat where the damper used to be ( I removed the damper to get the liner through) using a home made damper block off plate. To seal off, I cut out insulation blanket (rated at 2600F) in the shape of the damper with the liner hole cut out, and then did the same thing with a 20 gauge steel sheet of metal. Essentially was trying to make an insulated damper block off plate.

Questions:

1- Do you foresee it being a problem that the top 4 feet of the liner is not insulated? For reference, those 4 feet are in the part of the chimney that are above the structure of the actual house.
1a- if you think it is a problem, what's the best way to resolve *without* having the uninstall everything and pull the liner out.

2- I am having a really hard time attaching the steel sheet to the frame of damper which is made out of cast iron I think. My current plan is to use rutland furnace cement, however that stuff has to cure at 500F for an hour. Do you think that area will get that hot? I tend to think not.
2a- If the cement isn't a good solution, any other ideas?

Thanks everyone!

PS-here is a photo of the finished project. Will be undoing the hearth surround panels to finish closing off the damper once I get feedback from you all on best way forward.
1663088453949.png
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,392
South Puget Sound, WA
You could pack the upper 4 ft around the liner with roxul or kaowool insulation.
The block off plate doesn't need to be attached to the damper frame, though it could be. Cast iron is fairly easy to drill and tap if that is desired. Others place the block-off plate below the damper frame, drill into the masonry and use tapcons to hold it in place. A good quality silicone is better to seal the edges.
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
30,242
central pa
Hi all, I am just finalizing the installation of my new Ashley Hearth Fireplace Insert. A bit of background: I have an old stone fireplace with a 20 foot chimney chase. the chase is lined with clay, but am unsure of the condition of the clay. I installed a 20 foot flexible steel liner ( flexible really seems like a poor descriptor!) and insulated the first 16 feet of the liner (from the stove up) with a 1 inch thick insulation blanket from Rockford Chimney Supply. I am now trying to seal off the throat where the damper used to be ( I removed the damper to get the liner through) using a home made damper block off plate. To seal off, I cut out insulation blanket (rated at 2600F) in the shape of the damper with the liner hole cut out, and then did the same thing with a 20 gauge steel sheet of metal. Essentially was trying to make an insulated damper block off plate.

Questions:

1- Do you foresee it being a problem that the top 4 feet of the liner is not insulated? For reference, those 4 feet are in the part of the chimney that are above the structure of the actual house.
1a- if you think it is a problem, what's the best way to resolve *without* having the uninstall everything and pull the liner out.

2- I am having a really hard time attaching the steel sheet to the frame of damper which is made out of cast iron I think. My current plan is to use rutland furnace cement, however that stuff has to cure at 500F for an hour. Do you think that area will get that hot? I tend to think not.
2a- If the cement isn't a good solution, any other ideas?

Thanks everyone!

PS-here is a photo of the finished project. Will be undoing the hearth surround panels to finish closing off the damper once I get feedback from you all on best way forward.
View attachment 298973
You have the important part with regards to safety insulated but not the important part with regards to performance
 
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RamMasterFlash

New Member
Sep 13, 2022
11
Connecticut
You have the important part with regards to safety insulated but not the important part with regards to performance
You could pack the upper 4 ft around the liner with roxul or kaowool insulation.
The block off plate doesn't need to be attached to the damper frame, though it could be. Cast iron is fairly easy to drill and tap if that is desired. Others place the block-off plate below the damper frame, drill into the masonry and use tapcons to hold it in place. A good quality silicone is better to seal the edges.
Thanks for the reply and the tips. I was trying to avoid drilling, simply because this place is a rental and whenever I move I will have to put the damper back. As for adding the roxul/kaowool, do you think this would significantly impact performance?
 

EbS-P

Minister of Fire
Jan 19, 2019
3,548
SE North Carolina
Do you have 16” from the door to the wood floor. If not that would be much more of a concern to me than the 4’ of uninsulated
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
30,242
central pa
UhOh. No. It’s 13 inches from the door to the end of the stone floor. Is the risk that a log could fall out when I have the door open?
It's that and concern over radiant heat from the stove
 

EbS-P

Minister of Fire
Jan 19, 2019
3,548
SE North Carolina
UhOh. No. It’s 13 inches from the door to the end of the stone floor. Is the risk that a log could fall out when I have the door open?
Read the manual it will tell you wether or not the extension needs ember only or R value. I’m guessing R value. As the unit is flush on the floor. There are solutions.
 

RamMasterFlash

New Member
Sep 13, 2022
11
Connecticut
Read the manual it will tell you wether or not the extension needs ember only or R value. I’m guessing R value. As the unit is flush on the floor. There are solutions.
You know your business. Really appreciate the feedback.

This is from the manual: "A solid non-combustible floor, concrete or solid masonry, must extend 6” (153 mm) to either side of the body of the appliance and 17” (432 mm) in front of the face of the appliance. When combustible flooring falls within these minimum dimensions, it must be covered with a UL listed floor protector, with an R-Value of at lease 1.4"

Time to go down the rabbit hole of UL listed floor protectors...
 
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EbS-P

Minister of Fire
Jan 19, 2019
3,548
SE North Carolina
You know your business. Really appreciate the feedback.

This is from the manual: "A solid non-combustible floor, concrete or solid masonry, must extend 6” (153 mm) to either side of the body of the appliance and 17” (432 mm) in front of the face of the appliance. When combustible flooring falls within these minimum dimensions, it must be covered with a UL listed floor protector, with an R-Value of at lease 1.4"

Time to go down the rabbit hole o in h
You know your business. Really appreciate the feedback.

This is from the manual: "A solid non-combustible floor, concrete or solid masonry, must extend 6” (153 mm) to either side of the body of the appliance and 17” (432 mm) in front of the face of the appliance. When combustible flooring falls within these minimum dimensions, it must be covered with a UL listed floor protector, with an R-Value of at lease 1.4"

Time to go down the rabbit hole of UL listed floor protectors...
I did some searches once. This is one option but double check all the specs.
HY-C T2Ul3242Ww-1 Lined Type 2 Stove Board with Rounded Corners, 32" x 42" https://a.co/d/btNcmW5
 

RamMasterFlash

New Member
Sep 13, 2022
11
Connecticut
I did some searches once. This is one option but double check all the specs.
HY-C T2Ul3242Ww-1 Lined Type 2 Stove Board with Rounded Corners, 32" x 42" https://a.co/d/btNcmW5
Thanks. My research brought me to the same place. Just ordered this guy: Amazon product

Another question though: I have some R-19 fiberglass insulation sitting around. Could this be used for the top 4 feet of the chimney liner? I wouldnt dream of using that down by the actual stove, or even most of the chimney but am wondering if the temperatures at the top of a 20' stack would be low enough that using fiberglass instead of rockwool would be OK.
 
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RamMasterFlash

New Member
Sep 13, 2022
11
Connecticut
Cancel that last question. A buddy of mine had some Fire Resistant Stone Wool Insulation From Rockwool leftover. Just stuffed it down the chimney on all sides of the liner down 4 feet. The entire thing is now insulated.

Time for my maiden voyage to see how it works!

Thanks for all the excellent feedback guys. Much appreciated.
 

Iron mountain man

New Member
Nov 3, 2022
1
sn00kkii@YOU
You can purchase ceramic insulation on eBay. Rated from 2300 to 2600 degrees Fahrenheit...3200 degrees F melting point.
The stuff is amazing. I used 1” 3800 melting point but rated at 2800 working max temp, on a 5’ wide window unit and covered the framework then harder board siding over that with very small head trim screws .
If you want or need to use a larger head nail or screw you can paste over with furnace cement and using a stick or putty knife just form the wood grain look before it dries to match the harder board look.
This insulation was developed by NASA and used exclusively for ultra high temps in spaceships and rockets.
A torch applied to one side the 1/2” and you will feel a little warmth on the other Amazing around chimneys that come too close or added between the 2” clearance for more protection, when using the insulated chimney.
BTW This is what they use in between double wall chimneys now.
Just make sure no gaps or seams left without some overlap
You can also compress it. Unlike fibreglass it compresses itself when heated to resist more heat. Look it up and get your specs for safety and confidence.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
30,242
central pa
You can purchase ceramic insulation on eBay. Rated from 2300 to 2600 degrees Fahrenheit...3200 degrees F melting point.
The stuff is amazing. I used 1” 3800 melting point but rated at 2800 working max temp, on a 5’ wide window unit and covered the framework then harder board siding over that with very small head trim screws .
If you want or need to use a larger head nail or screw you can paste over with furnace cement and using a stick or putty knife just form the wood grain look before it dries to match the harder board look.
This insulation was developed by NASA and used exclusively for ultra high temps in spaceships and rockets.
A torch applied to one side the 1/2” and you will feel a little warmth on the other Amazing around chimneys that come too close or added between the 2” clearance for more protection, when using the insulated chimney.
BTW This is what they use in between double wall chimneys now.
Just make sure no gaps or seams left without some overlap
You can also compress it. Unlike fibreglass it compresses itself when heated to resist more heat. Look it up and get your specs for safety and confidence.
Not sure what any of that has to do with this thread