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Post by pinhead on Jul 30, 2018 8:10:38 GMT -8
That's not what I meant. Just place the 5 minutes riser on the floor level of the core. After that, build around with the same firebricks of the firebox. And I mean here in a running bond with the rest of the firebox so it will provide very good support for the riser to stay in place. And back fill it with perlite/clay, clay/straw, or something else in such a way that the riser can't move in any direction. This is how I did mine and it hasn't moved at all.
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Post by pinhead on Jul 27, 2018 5:08:36 GMT -8
There are three densities commonly available , yes. In metrics: 96 kg/m³, 128 kg/m³ and 160 kg/m³, corresponding with #6, #8 and #10. Last time I used the #8 density and 1" thickness for to wrap around an 8" steel pipe. I'd find it hard to do with four hands and almost impossible with two. During another workshop we used #6 to wrap around a square riser and it worked just fine. So, I'd think you would do fine with the 96 kg/m³ aka #6 density. Maybe Pinhead knows what he was using at the time? edit: By the way, the numbers 6, 8 and 10 should be read as pcf, pounds per cubic foot. Sorry for the late reply. My first heat riser (still going strong) was 6# density.
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Post by pinhead on Jun 7, 2018 12:24:18 GMT -8
Thanks pinhead. Having read about yours and other peoples use of half barrels as a bell/bench IV decided to try and do the same. Bench will be a 15ft L-shape. I'd like to use a brick duct to carry the smoke as far as the start of the curve in the L before introducing it in to the bell. The idea being that it should encourage the hot gases to fill the chamber faster. The exit will be at the bottom next to the combustion unit. Can you see any potential problem with this? P.S. Thank you for the inspiration. The ceramic fibre has saved me a lot of time and money No problem at all as long as as you build it with enough CSA as to not cause a flow restriction.
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Post by pinhead on Jun 4, 2018 9:48:53 GMT -8
Thanks for the comments. A bell bypass would have been nice but the chimney is made from huge pieces of stone that are almost impossible to cut and remove. To pierce an opening for a bypass there would have made the project unworkable. It likely wouldn't have been necessary to add another chimney entry; all that is required for a bypass to work is the gasses have to bypass the heat exchanger. Whether this is done by directly feeding into a higher portion of the chimney, or flowing through an internal path to the chimney is immaterial as long as heat isn't lost on the way.
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Post by pinhead on Jun 4, 2018 9:43:14 GMT -8
Great thread. I'm planning on using the same riser for an 8" j' tube. Do you have any idea how this would affect the barrel top/riser gap? I'm thinking 2-3 inches... The insulation material shouldn't have any effect on the usable top-gap, though I build all of my stuff (both J and BB style) with a foot or more top-gap; I personally see no advantage of a small top-gap. HOWEVER, I've spent most of my time working with Batch Boxes so I don't have as much intuition with regards to tuning a J-tube.
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Post by pinhead on May 30, 2018 12:20:51 GMT -8
A bell bypass would have been a much more effective way to get the gas moving the right direction. Even if the BB had started smoking-back, the bypass would quickly get it moving in the right direction.
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Post by pinhead on May 11, 2018 8:51:22 GMT -8
In my experience, that would be acceptable; I have a 7-inch batch box feeding into a roughly 15-foot tall 6-inch chimney and it works well enough.
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Post by pinhead on Apr 9, 2018 10:47:48 GMT -8
thanks vortex for the suggestion. auxiliary bell has been designed to compensate for the lack of heat on the left side due to the presence of the core. I may be misunderstanding your purposes here, but as I see it, the auxiliary bell will be the very last area to receive heat in this design - much like a low bench will likewise be the last area to receive heat. Likewise, the overall temperature will be much lower - as the gas temperature will necessarily be lower when compared to the upper portions of the primary bell in order to reach the small "door" leading to the auxiliary bell. On the other hand, the small gap between the core and the wall on the left side is sufficient by itself to allow heat to flow to that area - and thus heat that wall. There is no need for a "secondary" or separate bell to move heat to that area - unless you specifically want it to be of lower intensity.
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Post by pinhead on Apr 5, 2018 8:38:01 GMT -8
That looks like quite the undertaking! Since I don't know the relative output of the DSR, I'd be hesitant to apply such a large mass to it. OTOH I only have experience with J's and PBB's.
You will definitely, absolutely, unequivocally need a bypass (or two) to get it started from cold.
EDIT: I'm looking more closely at your SKP and noticed a door you can open/close. I'll have to wrap my head around the exhaust path before I can make any suggestions!
EDIT 2: Ok now I see!
Only thing I'd note is, from the looks of it, the "auxiliary" bell on the left side of the assembly won't heat up for a long, long time. This may be by design, though I doubt it'll ever get up to temp under normal operating conditions.
This is basically the design that I had in mind when I built my PBB Cellar Rocket. I don't see why it wouldn't work - provided the DSR has enough output!
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Post by pinhead on Apr 5, 2018 8:32:57 GMT -8
I don't imagine a 10-inch J Tube would put out more heat (or even as much) as an 8-inch Batch Box.
Other than the logistics of physically building a large J, I don't see any specific caveats to watch out for that wouldn't likewise apply to an 8 inch batch build.
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Post by pinhead on Mar 12, 2018 7:36:29 GMT -8
You might want to read the Small Scale Development thread. It's long but it covers the difference between burning with and without tertiary air.
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Post by pinhead on Mar 9, 2018 5:53:29 GMT -8
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Post by pinhead on Mar 2, 2018 7:31:40 GMT -8
chrisz , Be careful, if you fill an open hot crack, on the next firing there will be an even greater push on the sides ! On old tepluschka stoves they used to fill the top of their vaults with sand and it turned out to be a very bad idea because the sand would go inside the dilatation cracks and at each firing cycle the dilatation would be stronger on the sides of the vaults because the vault was becoming larger with the sand coming in. If you make a system to close your secundary air after the firing, you'll get some extra percents efficiency. I can't put a number on it, but i'm sure it's not negligible. Hope it helps,, Regards, I tried that very thing (sand in the cracks) on one of my first bell benches. Was a bad idea for that very reason.
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Post by pinhead on Mar 2, 2018 7:25:41 GMT -8
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Post by pinhead on Mar 2, 2018 7:21:27 GMT -8
You could an exhaust heat exchanger such as this:
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