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Post by Karl L on Oct 25, 2022 8:50:19 GMT -8
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Post by Dan (Upstate NY, USA) on Oct 26, 2022 9:46:27 GMT -8
I used it around my primary fire box to insulate around the structure, when I had to rebuild it was still working as insulation but had to put new rockwool in due to the binder no longer holding the rockwool together. When I pulled it apart it would not hold its form anymore.
So if you use it outside the flame path and it is friction fit into place it will be fine.
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Post by Karl L on Oct 26, 2022 10:00:43 GMT -8
Thanks, Dan. Did you have any experience of what kind of fumes are given off when the binder is burnt off? In the use I am thinking of, these fumes would enter the living space.
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Forsythe
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Instauratur Ruinae
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Post by Forsythe on Oct 26, 2022 19:23:22 GMT -8
Thanks, Dan. Did you have any experience of what kind of fumes are given off when the binder is burnt off? In the use I am thinking of, these fumes would enter the living space. Formaldehyde and trace ammonia from the decomposition of the phenolic formaldehyde resin used to make the rockwool hydrophobic. Can be as high as 5% formaldehyde, but appears to be 3% for industrial gas-vent tube insulation. If you were to proceed with this idea, it would be advisable to burn-out (or rather: "bake-off") that formaldehyde prior to indoor installation. (but be careful not to exceed the metal's thermal tolerance and damage / de-alloy / carburize / embrittle the steel. ...but it wouldn't be code compliant no matter how you approached it... (source: www.rockwool.com/syssiteassets/o2-rockwool/documentation/safe-use-instruction-sheet/safe_use_instruction_sheet-rockwool.pdf ) [source: www.rockwool.com/north-america/advice-and-inspiration/faq/ ) (source: www.greenhomeguide.com/know-how/article/choosing-the-best-insulation-delivers-energy-savings ) I looked into something kind-of similar a while back because I was disgusted by the utterly insane price of 316L class A chimney pipe and the non-existence of 316Ti double-walled rigid stovepipe. ( The code-rated flue pipe here costs more than the materials to build a medium-sized masonry cooktop heater... and the flue pipe is only expected to last 8 years before needing replacement because the 200 and 400 series "stainless steel" they use on the liner interior isn't corrosion resistant nor "stainless" by any practical, metallurgical sense of the term... but the 316L and 316Ti flexible liners designed as masonry chimney inserts and gas vents hold up a lot better to the inevitable condensation on the upper part of the chimney near the roof exit. ...I also learned that running a 6" zirconia ceramic fiber insulated liner insert through an existing 10" double-walled chimney stack (made by a manufacturer who's no longer in business) is not code compliant, even though it would be nearly 3 times as fireproof, capable of containing multiple sustained chimney fires without breaching or transmitting heat to combustable surfaces, and nearly impervious to gas leaks from snow load shifts, earthquakes, etc. which can ply open leaks in rigid double-walled pipe. Code here literally insists that you use less-safe materials in your woodburning appliance chimneys than that available for flexible gas vents, and you're not allowed to build something safer, yourself, unless it's encased in a masonry chimney stack on the exterior side of the building... which just-so happens to kill the chimney draft by excluding the chimney from the heated building envelope, and which promotes smoke-back and potential carbon monoxide accumulation in the residence... which is totally fine by the local code officers. 🙄) I say all that rant just to point out that: if following code is important to you to avoid fines and/or loss of homeowner's insurance, then —in the vast majority of english-speaking countries— gas appliance flue liners probably won't be an option to attach to a wood burning mass heater, (no matter how many ways you triple- or quadruple- reinforce the thermal, structural, and corrosion-resistance safety features to higher tolerances than commercially-available and "approved"-but- less-safe-and- less-durable products. Actually-safe functionality and preventing structure fires, property damage, injury, or loss of life are not within the code-system's actual goals. Coercing you to comply with making an approved product-purchase from a list of commercial options is. Unfortunately, the UL and ASTM system is designed to prevent lawsuits — not to prevent fire hazards.
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Post by Karl L on Oct 27, 2022 1:29:04 GMT -8
Thanks for all that information and experience, Forsythe. I've asked for the datasheet for that particular product to find out more...
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Post by Dan (Upstate NY, USA) on Oct 27, 2022 4:17:43 GMT -8
Mine was sealed in masonry so I am sure it off gassed but it came out so slow we didn't notice on the first build or the rebuild.,
And nothing I build meets local code, but all I build is safer than code buildings.
"It takes an engineer to make something that barely stands"
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Post by fiedia on Oct 28, 2022 5:19:01 GMT -8
I did some trials with glass wool insulated tubes on rocket HR in my garden. It stinked so much that my neighbor came in wondering if my house was on fire.
My brother had its roof burning although there was 7 meters rockwool insulated pipes between the stove and the roof. He must have really overfilled his stove because I have been using such a double pipe with my own stove at more than 500°C without problem for more than 15 years (although there might have been some offgassing).
Lately, I got some 250mm (10') pipes for free. So I bought stainless 200mm (4') pipes and filled the gap with vermiculite. Added some clay+vermiculite mix on both ends to keep the bulk vermiculite inside. Did not fire it up yet but I expect no offgasing from clay or vermiculite (and a much cheaper solution).
Thermal resistance might be lower but it will change with temperature (fibers seems not so efficient at insulating radiant heat at high temperature). My stainless steel pipes withhold 750 °C for many years.
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Post by Dan (Upstate NY, USA) on Oct 28, 2022 5:39:35 GMT -8
7 meters long, or 7cm thick?
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Forsythe
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Instauratur Ruinae
Posts: 208
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Post by Forsythe on Oct 28, 2022 15:11:29 GMT -8
To me that sounds more like a chimney fire from a creosote deposit catching fire within the tube and burning the adjacent roof.
That tends to be a lot more common with traditional wood stoves that people damper down and smolder for long overnight burns, which gums up the chimney with tars and carbon... stuff that all gets burned off in a properly designed rocket stove or masonry heater, so it never has a chance to accumulate in the chimney. Burning low temperature fires in a firebox is the #1 cause of high temperature chimney fires.
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Post by fiedia on Oct 29, 2022 7:03:49 GMT -8
Fiedia : Dan :
Yes Dan, here we use to put 7m rockwool between our stove and our roof. It keeps us warm during winter. In fact we live and sleep in rockwool holes. it is so fine when our skin and lungs itch like hell.
Forsythe, you are certainly right about chimney fire. The point is that one buys those nice insulated pipes and believes it's fireproof. It does not prevent you from chimney fire lightning your roof. One has to keep distance and/or plaster between the pipe and the wood beams.
In addition, with or without chimney fire and binder offgassing, rockwool is a harmful mineral fiber.
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Post by Dan (Upstate NY, USA) on Oct 29, 2022 12:43:41 GMT -8
Thought it was a typo since we were discussing thickness, relax
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Forsythe
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Instauratur Ruinae
Posts: 208
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Post by Forsythe on Oct 29, 2022 13:34:34 GMT -8
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Post by fiedia on Oct 29, 2022 23:21:56 GMT -8
Sorry, forgot the smiley... Do not worry, I was just kidding, irony...
Some pictures of my vermiculite insulated tubes.
Filling with vermiculite:
Clay + vermiculite top and bottom:
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Forsythe
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Instauratur Ruinae
Posts: 208
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Post by Forsythe on Nov 8, 2022 0:05:00 GMT -8
Not that I would ever be inclined to violate the ever-so-wise and safety-oriented and material-savvy local building code in my area... ...but I found these 305 Stainless Steel diesel-exhaust pipes which are 5" inside diameter, easily stackable, easily modified to lock together with SS zip-tie clamps, easily sealed by common hi-temp sealants, and can be wrapped in basalt fiber and/or ceramic fiber to make your own insulated double-, triple-, or quadruple-walled flue pipe for less than half of the cost (per-foot) of the inferior grades of stainless steel class-A stove pipe. And it's 5" in diameter... which is like pulling teeth to find in the US (I've only found ONE supplier who stocks 5" class A chimney pipe in the whole of the contiguous US. And their's is only 304 stainless steel on the outside. ...Y'know... where it *appears* shiny to passing glances ...and where problematic corrosive condensation doesn't occur. So flipping UN-useful, that. On Ebay: www.ebay.com/itm/175400797955On Amazon: a.co/d/3afhmYN304 stainless steel is roughly 18/8 stainless, while 305 is roughly 18/10 (or better). It's *almost* 316 grade, except that it lacks the tiny inclusion of molybdenum that 316 has. Oh, and these are also 16 gauge... while the Class-A pipe is all of 22 gauge, which is approximately half the thickness. ...so...y'know... more robust and durable in literally every way. And they will slide within an existing, cheaper, 6" double-walled stove pipe... in case that's helpful. Not that I would ever encourage anyone to violate their local building code. That would be simply.... prudent illegal.
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Post by pinhead on Nov 11, 2022 7:29:04 GMT -8
Some pictures of my vermiculite insulated tubes. I've done that before and I found that after a while the vermiculite will settle which leaves an open gap at the top. I just added more to the top after a few months but it's something to keep in mind if installing in a permanent configuration.
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