Combination Ceiling Support & Attic Shield unit

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arkady

New Member
Dec 22, 2021
1
Appalachia, USA
Greetings everybody. Does anybody have the "DuraTech Square Ceiling Support Box with Attic Insulation Shield"?

If possible, I'd like to run my single-wall pipe up to the ceiling support box, and then have the chimney pipe run through the attic on the other side.

What I can't seem to find out is whether I need to get a separate adapter for the stove-to-chimney, or if the ceiling support box already has the adapter built in. It seems to me that most ceiling support boxes work that way. Any help would be appreciated.
 

EatenByLimestone

Minister of Fire
You're in luck! You only have to run the class A down to the ceiling. You can run singlewall up to the ceiling.
 

EatenByLimestone

Minister of Fire
A piece attaches to the bottom of the chimney and sticks down 8nto the room. The singlewall slides up and over it. The singlewall will fit in your stove coller.
 

kennyp2339

Minister of Fire
Feb 16, 2014
6,604
07462
The ceiling support box has a welded metal ring on the inside for the class a to connect to, rest the class a on it and do a half turn and it will lock in.
There should also be a 6" stainless steel metal ring with a 3" wide band, you take that ring and snap it in from the room side of the support box, it will only fit halfway, then your female side of the single wall pipe connects to that; male end always points down towards the stove.
 

Highbeam

Minister of Fire
Dec 28, 2006
19,871
Mt. Rainier Foothills, WA
I own two of the duravent brand square ceiling support boxes that are really tall to also act as an insulation shield.

The class a just drops in and locks in from above. The snout that sticks down into the room needs something before you can attach to it with stove pipe. There is a double wall adapter that screws on or a single wall “tailpiece” that pushes in to the snout and snaps into place for single wall.
 

begreen

Mooderator
Staff member
Nov 18, 2005
94,654
South Puget Sound, WA
Normally in this situation a tall support box is not used. If the ceiling is not a cathedral-style ceiling then their standard ceiling support is what is recommended. DuraVent makes them in round or square. Duravent makes a cylindrical attic insulation shield that mates with it.
We have the round support for a cleaner, minimal look. I painted the trim ring white to further minimize the visual impact.

Screen Shot 2021-12-23 at 9.41.40 AM.png IMG_2193.jpg
 

whatyousmokin

New Member
Oct 10, 2021
38
43011
I own two of the duravent brand square ceiling support boxes that are really tall to also act as an insulation shield.

The class a just drops in and locks in from above. The snout that sticks down into the room needs something before you can attach to it with stove pipe. There is a double wall adapter that screws on or a single wall “tailpiece” that pushes in to the snout and snaps into place for single wall.
What do you use to cover the support box? Appears our installation is a 6" Duravent 24" square ceiling support box and the height of the support box is acting as the shield. There is no cover to prevent anything from dropping down into the area between the inner edges of the box and the chimney pipe. Does anyone have any suggestions? Can an actual insulation shield and cover be installed with this current set-up? This is not a cathedral ceiling but did read Duratech says that this support box can be used on flat ceiling.

install support box.jpg ceiling.jpg
 
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EatenByLimestone

Minister of Fire
My shield is circular and angles in to form a cone around the pipe. Check out Metalbestos pipe by Selkirk.

It wouldn't be hard to form a flat 2 piece cover out of sheet metal with a brake and some tin snips. It'd be better to secure it with pop rivets or screws, but that could cause problems as it might be considered altering the piece. I'd probably just make it large and set it on top. Its not like it'll get disturbed in the attic.
 

whatyousmokin

New Member
Oct 10, 2021
38
43011
I wonder what the odds are of ever having anything drop right inside that box next to the pipe. I feel like I am working up an ulcer over the minute possibility of a pending disaster that may never happen. By chance, does anyone know what that chimney pipe would feel like temperature-wise when the stove is operating at maximum efficiency (stove rated at up to 60,000 BTU)-would it be warm to the touch or much higher? Is the 2" gap around the pipe to combustibles mostly for a safety factor in the case of a chimney fire?
 

Highbeam

Minister of Fire
Dec 28, 2006
19,871
Mt. Rainier Foothills, WA
What do you use to cover the support box? Appears our installation is a 6" Duravent 24" square ceiling support box and the height of the support box is acting as the shield. There is no cover to prevent anything from dropping down into the area between the inner edges of the box and the chimney pipe. Does anyone have any suggestions? Can an actual insulation shield and cover be installed with this current set-up? This is not a cathedral ceiling but did read Duratech says that this support box can be used on flat ceiling.

View attachment 288767 View attachment 288768
Nothing on mine, the open top of the box is above insulation level and nothing falls in there. I’ve checked. Passed inspections just fine. I’m sure you could add something like a common storm collar if you’re worried. Duravent tech support could provide reassurance or sell you a part number.

I recommend checking the box after insulation contractors blow in attic insulation just in case they got sloppy.
 

begreen

Mooderator
Staff member
Nov 18, 2005
94,654
South Puget Sound, WA
Nothing on mine, the open top of the box is above insulation level and nothing falls in there. I’ve checked. Passed inspections just fine. I’m sure you could add something like a common storm collar if you’re worried. Duravent tech support could provide reassurance or sell you a part number.

I recommend checking the box after insulation contractors blow in attic insulation just in case they got sloppy.
The dilemma is that we know nothing of the future of the house and what will happen in the attic. Will insulation get blown in, will the roof get redone, will a remodel happen, or will squirrels get in and build nests in a nice warm spot? For peace of mind, cover it.

This is a sad illustration of what can happen when insulation is blown in the attic against chimney pipe. They did it this fall. About a month ago they had a small chimney fire which would have been protected by an attic insulation shield. Unfortunately, there was no insulation shield installed.

attic insulation shield.jpg
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
29,225
central pa
Nothing on mine, the open top of the box is above insulation level and nothing falls in there. I’ve checked. Passed inspections just fine. I’m sure you could add something like a common storm collar if you’re worried. Duravent tech support could provide reassurance or sell you a part number.

I recommend checking the box after insulation contractors blow in attic insulation just in case they got sloppy.
Do you not have mice or squirrels where you live??
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
29,225
central pa
I wonder what the odds are of ever having anything drop right inside that box next to the pipe. I feel like I am working up an ulcer over the minute possibility of a pending disaster that may never happen. By chance, does anyone know what that chimney pipe would feel like temperature-wise when the stove is operating at maximum efficiency (stove rated at up to 60,000 BTU)-would it be warm to the touch or much higher? Is the 2" gap around the pipe to combustibles mostly for a safety factor in the case of a chimney fire?
It is a safety factor Incase you ever have a chimney fire. And yes it is absolutely a possibility for anyone heating with wood.
 

Highbeam

Minister of Fire
Dec 28, 2006
19,871
Mt. Rainier Foothills, WA
Do you not have mice or squirrels where you live??
Sure, but I’m not worried about them falling into that skinny slot. I’d worry more about them chewing my electrical wires and starting a fire. Do you have all of your wires in steel conduit?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
29,225
central pa
Sure, but I’m not worried about them falling into that skinny slot. I’d worry more about them chewing my electrical wires and starting a fire. Do you have all of your wires in steel conduit?
Armored cable yes well almost. Do you have any idea how many mouse nests I have cleaned out of support boxes through the years?
 

Highbeam

Minister of Fire
Dec 28, 2006
19,871
Mt. Rainier Foothills, WA
The dilemma is that we know nothing of the future of the house and what will happen in the attic. Will insulation get blown in, will the roof get redone, will a remodel happen, or will squirrels get in and build nests in a nice warm spot? For peace of mind, cover it.

This is a sad illustration of what can happen when insulation is blown in the attic against chimney pipe. They did it this fall. About a month ago they had a small chimney fire which would have been protected by an attic insulation shield. Unfortunately, there was no insulation shield installed.

View attachment 289252
Yep, like I said, if you’re worried and want to go above and beyond then you can do lots of things up to and including not burning.

Does code require that insulation shield be capped? Does the manufacturer?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
29,225
central pa
Yep, like I said, if you’re worried and want to go above and beyond then you can do lots of things up to and including not burning.

Does code require that insulation shield be capped? Does the manufacturer?
Many manufacturers do require it yes. And if they don't I see that it is very irresponsible.

And if the manufacturer requires it code does as well.
 
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whatyousmokin

New Member
Oct 10, 2021
38
43011
Do you have any idea how many mouse nests I have cleaned out of support boxes through the years?

Based on the conversations here, I do plan to have our support box outfitted with some sort of storm collar--not just a flat lid that fits over the box, but a collar that would divert anything away from the chimney in the attic. However, my question remains, how hot does that chimney pipe get under normal operating conditions? Is it possible the only time I would worry about our current installation is if we were to have a chimney fire and combustibles were right next to the chimney pipe? The combustibles outside the pipe wouldn't necessarily cause a chimney fire, right? More likely, a chimney fire would ignite the combustibles (mouse nests) lying right next to it? I am not trying to be a smart ass here, just want to understand the real risk without having to scream and yell at the installers for cutting corners and putting me and my pup in any sort of danger for not covering that support box. From everything else I can see, the installers did an excellent job. But I'm just a homeowner with zip. point. chit. knowledge on this stuff.........
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
29,225
central pa
Based on the conversations here, I do plan to have our support box outfitted with some sort of storm collar--not just a flat lid that fits over the box, but a collar that would divert anything away from the chimney in the attic. However, my question remains, how hot does that chimney pipe get under normal operating conditions? On our double wall connector pipe inside the house, I can lay my hand on that all day long, as long as the blower fan is running, nothing would combust. If the outside of chimney pipe in the attic is even more protected, is it possible the only time I would worry about our current installation is if we were to have a chimney fire and combustibles were right next to the chimney pipe? I am not trying to be a smart ass here, just want to understand the real risk without having to scream and yell at the installers for cutting corners and putting me and my pup in any sort of danger for not covering that support box. From everything else I can see, the installers did an excellent job. But I'm just a homeowner with zip. point. chit. knowledge on this stuff.........
The risk is relatively low unless you have a chimney fire. But it's still there. Even just spacing out and leaving the air open or the door cracked open can lead to really high pipe temps that would greatly increase risk. But you would have to check the manual for your pipe. If it calls for a cover they screwed up and have to come back and fix it. If not then I would still want it but you can't expect them to do it at no cost to you
 
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whatyousmokin

New Member
Oct 10, 2021
38
43011
Thanks bholler. (I edited my post after you responded, I can not always lay my hands on the double wall connector pipe even with fan running, , stove is really running hot today;), really loaded up and have it blasting here.
So, what is a typical, normal range of temps on class A chimney pipe -- (our double wall connector pipe is connected directly to chimney pipe in support box, if that makes any difference), providing I don't space out and forget to completely latch door on stove? And yes, that has happened.😱
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
29,225
central pa
Thanks bholler. (I edited my post after you responded, I can not always lay my hands on the double wall connector pipe even with fan running, , stove is really running hot today;), really loaded up and have it blasting here.
So, what is a typical, normal range of temps on class A chimney pipe -- (our double wall connector pipe is connected directly to chimney pipe in support box, if that makes any difference), providing I don't space out and forget to completely latch door on stove? And yes, that has happened.😱
I honestly don't know what normal operating temperature on the outside of class a is I have never measured it.

And it has happened to most of us who heat with wood
 

begreen

Mooderator
Staff member
Nov 18, 2005
94,654
South Puget Sound, WA
Class A can get above 130º surface temp in normal operation if the flue gases are hot, say >600º. Long-term exposure to 180º temps can set up conditions for pyrolysis.
 

whatyousmokin

New Member
Oct 10, 2021
38
43011
Pyrolysis??? Oh My!! Sounds ominous:ZZZ -- like I need to be getting on the installers sooner rather than later. Thank you all!