UL 1777 Testing data for insulated liners?

[farmwithjunk]

I've been reading some data on clay flue liners and even data on Thermix testing but I don't see any on insulated flex or rigid liners. I'm curious to see the performance of 1/2 insulation. Its almost hard to believe that a simple 1/2 (really less than that) blanket can slow enough heat transfer even at 0/0 clearance.

For example Duravent has this in one of their documents showing how much better pour in insulation works compared to a code approved clay liner.

What I don't understand is how tile lined chimney's, even when code approved, do not appear safe at continuous high temp usage. 1" gap wood gets well over the min for wood impacted by pyrolysis. I doubt most stoves can contain enough wood to sustain 1000F flue temps for more than a few hours but I could see continual reloading being dangerous even in approved chimneys. There are posts on Reddit all the time where people show glowing pipe and have no clue that they can't leave the damper open all the time. Apparently there is a some safety factor in there and actual 200-250F ignition must be quite rare.

 

[retlaw]

I've been reading some data on clay flue liners and even data on Thermix testing but I don't see any on insulated flex or rigid liners. I'm curious to see the performance of 1/2 insulation. Its almost hard to believe that a simple 1/2 (really less than that) blanket can slow enough heat transfer even at 0/0 clearance.

For example Duravent has this in one of their documents showing how much better pour in insulation works compared to a code approved clay liner.

What I don't understand is how tile lined chimney's, even when code approved, do not appear safe at continuous high temp usage. 1" gap wood gets well over the min for wood impacted by pyrolysis. I doubt most stoves can contain enough wood to sustain 1000F flue temps for more than a few hours but I could see continual reloading being dangerous even in approved chimneys. There are posts on Reddit all the time where people show glowing pipe and have no clue that they can't leave the damper open all the time. Apparently there is a some safety factor in there and actual 200-250F ignition must be quite rare.

View attachment 336000

Note that it's not just a 1" gap to wood, but an enclosure around the chimney....that will hold in a lot of heat. At least that's the way I read it.
Search for the NIST publication titled Thermal Performance of Masonry Chimneys and Fireplaces for some more data.

 

[farmwithjunk]

Note that it's not just a 1" gap to wood, but an enclosure around the chimney....that will hold in a lot of heat. At least that's the way I read it.
Search for the NIST publication titled Thermal Performance of Masonry Chimneys and Fireplaces for some more data.

I didn't see any mention of insulated stainless other than 45mm asbestos so it kind of gives away it's age lol.

From what I've seen they only test up to 8 hours and a mention of 16 hours. It seems like the 1000F continuous on a code approved clay lined chimney could far exceed safety tolerances. You'd really have to work at it to maintain 8+ hours of 1000F though, I could being home 24/7 if I was trying.

 

[bholler]

I didn't see any mention of insulated stainless other than 45mm asbestos so it kind of gives away it's age lol.

From what I've seen they only test up to 8 hours and a mention of 16 hours. It seems like the 1000F continuous on a code approved clay lined chimney could far exceed safety tolerances. You'd really have to work at it to maintain 8+ hours of 1000F though, I could being home 24/7 if I was trying.

That test is only partial though. They didn't test to 2100 for chimney fire conditions

 

[EbS-P]

Do building codes even require UL testing? there is a reason so many houses burned down due to chimney fires.

 

[bholler]

Do building codes even require UL testing? there is a reason so many houses burned down due to chimney fires.

No not nessecarily. Unlisted clay tiles in a masonry chimney are perfectly acceptable if that chimney is built to code. Once you go to a listed system the code just refers to manufacturers instructions

 

[farmwithjunk]

No not nessecarily. Unlisted clay tiles in a masonry chimney are perfectly acceptable if that chimney is built to code. Once you go to a listed system the code just refers to manufacturers instructions

I'm not saying they aren't safe but I'm saying the data seems to contradict them being safe with the temps published, at least that's how I read it. These older tests are in CSIA's Chimeny Fire white paper and sound like they might be within code. Duravent specifically says "code approved tile lined chimney" and it shows temps of the wood going over the safety threshold and climbing. Perhaps I'm not understanding it but it would seem 1000F continuous isn't actually safe after extended periods.

Kind of a moot point as my 1979 chimney has a 1" gap (with insulation between it and framing) and I'm going a 0 clearance liner. What I can't find is this type of testing for a modern insulation wrap.

 

[mellow]

Pipe that comes pre insulated has to be done right at the factory. DIY "wrappers" can still screw it up, seen it done many times where they leave a gap in the insulation due to ovalizing the pipe or other stupidity.

 

[farmwithjunk]

Pipe that comes pre insulated has to be done right at the factory. DIY "wrappers" can still screw it up, seen it done many times where they leave a gap in the insulation due to ovalizing the pipe or other stupidity.

No doubt people screw it up but you'd have to be kind of careless IMO. There are detailed instructions and my wrap for example over laps about 6". Same crowd that might argue that insulation is a money grab or ask if glowing pipes is normal.

 

[stoveliker]

Not many people are as careful as you!
(which is a compliment)

 

[mellow]

You can install the wrap correctly and still rip it on an offset tile if you are not careful pulling it down the chimney, or do not install the chicken wire wrap (which I have seen).