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Post by satamax on Sept 9, 2018 2:36:56 GMT -8
Hi everybody.
Well, i am calling every one of you, five minute riser owners.
I know Doug's has lasted since January 2017.
The questions for you,
how did it resist so far?
Did the superwool sag?
Do you have inside pictures of it now, after X amount of time burning?
I'm considering it for my next build. But i'd rather avoid mistakes i have done in the past.
Thanks a lot guys.
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Post by wiscojames on Sept 10, 2018 11:43:05 GMT -8
Wow there's not as many responses as I thought there would be. I am using a 5-minute riser for my outdoor cook stove. It is a 6in batch heating a big cast-iron Plancha. I've run it hard many times this summer and can see no degradation. This is not quite the same as heating a house with it though. If you can get to it for repairs it's a no brainer, I think, given the cost in money and time.
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Ralf
New Member
Posts: 42
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Post by Ralf on Sept 10, 2018 12:43:25 GMT -8
Hi, the principle of five minute risers is also used in ceramic kilns used for Raku, a kind of ceramic that is fired (and cooled) very rapidly. Search for "Ochsner Kübel Raku" to see pictures. As they see a lot of thermal stress and abuse I think such a riser should last quite long. However there´s one additional detail the potters use to keep the ceramic fibre in place: They "sew" the ceramic fibre blanket to the supporting metal casing. Knobs with two holes are either made of pre-fired fireclay ceramics or Inconel metal, Kanthal wire is used as a sewing thread to fix them on the inside of the fibre blanket, and poked through to two corresponding little holes in the metal casing. If you want to be 100 % sure to have no sagging try this.
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Post by satamax on Sept 10, 2018 12:51:14 GMT -8
Thanks guys.
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Post by pinhead on Sept 11, 2018 10:13:14 GMT -8
Mine is still going strong without any visible degradation, though I haven't had to light it yet this season.
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Post by satamax on Sept 11, 2018 17:26:15 GMT -8
Thanks Doug.
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Post by scottiniowa on Sept 16, 2018 5:25:53 GMT -8
I have had a 1" thick "rock wool" blanket inside the fire box at top, where NO wood actually touches it, but certainly subjected to roar of the fire/air actions... This was during a temp burn testing period... 20-30 burns ... Other than ash on it, you couldn't really tell it was there.
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Post by invention1 on Mar 8, 2019 9:43:43 GMT -8
I had to tear down a stove after several weeks due to mortar issues, but the 5 minute riser looked fine! I built a 6" 5 minute riser out of an 8" galvanized air duct and some 1" ceramic fiber blanket. I used some rigidizer on the blanket to make sure it stayed in shape (probably overkill) and also used some small ceramic hollow rods tied in place with nichrome wire at the top, just to make sure everything held together. Also probably overkill. The same material survived in a prototype stove for a few dozen burns. It was outside, I kept it protected from rain, because I found out the hard way that wetness will destroy ceramic fiber sheets and blankets, turning them into a soggy mess. At the teardown, the material was fine, a bit blackened at the top but basically unchanged inside the tube. The metal duct was mostly blackened, but in one area where is was in contact with the metal bell, it was blue in some areas, indicating it had reached up to 540F/282C - ish. So far it has proved successful.
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Post by drooster on Mar 8, 2019 9:54:30 GMT -8
Wow there's not as many responses as I thought there would be... Perhaps noone saw this thread at the time. This latest bump puts it active again.
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Post by DCish on Mar 8, 2019 10:53:52 GMT -8
I have 20+ burns on a 4" j tube core that runs an converted gas grill. No degradation observed.
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Post by Vortex on Mar 8, 2019 11:12:21 GMT -8
I noticed on that strip of ceramic blanket that I cut and used to make the restriction in the afterburner, that the surface has turned a bit yellowish and feels a bit more rigid and crunchy than the rest, but otherwise is as good as new.
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Post by DCish on Mar 9, 2019 12:46:43 GMT -8
I noticed on that strip of ceramic blanket that I cut and used to make the restriction in the afterburner, that the surface has turned a bit yellowish and feels a bit more rigid and crunchy than the rest, but otherwise is as good as new. I suspect you have much higher temps than my piddly grill rocket - can't wait to hear the numbers when your sensors come in!
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Post by pinhead on Mar 11, 2019 11:45:30 GMT -8
The home of my original 5-minute riser will be torn down some time this spring; the property was sold and we had to move out. Is a perfect time to get some pics of how everything is holding up. This will have been the longest-running 5-minute riser in existence so I'll be able to definitively show its longevity.
I can't say it'll be real soon so this post may be somewhat of a tease... But I'm not going to leave my BB RMH there!
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Post by esbjornaneer on Mar 19, 2019 2:43:59 GMT -8
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Post by gadget on Mar 19, 2019 7:42:36 GMT -8
I noticed on that strip of ceramic blanket that I cut and used to make the restriction in the afterburner, that the surface has turned a bit yellowish and feels a bit more rigid and crunchy than the rest, but otherwise is as good as new. Interesting on the color change. I wonder if some of the magnesium in wood ash has fused with your high alumina fibers. Maybe your forming some cordierite in there.
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