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Post by permaculturebob on Dec 14, 2018 14:28:41 GMT -8
There were no actual dimensions given, other than in terms of fire bricks for the dsr, This has the sketchup file way down the page I found it here Testo does sound out of my range for asmuch as I might use it- like you said, an expensive hobby. I'll have to settle for my nose and watching the secondary burn characteristics
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Post by permaculturebob on Dec 14, 2018 9:00:30 GMT -8
Looking at some of the preliminaries of the DSR2 it almost looks like the batchbox and riser almost fit into the same footprint as the DSR. If that is the case I could modify my DSR without too much trouble, maybe get it back running the same day. My reason is mostly that a shorter batch box would be more to my taste, the original dsr design is a bit too long and narrow, also, it appears that when cooking, any pots seem to lower the temps above the port to the point where soot deposits on the spot where the pot is. Likely having that secondary burn start down level with the firebox would keep temps higher for a longer time giving a cleaner burn when cooking. The DSR is performing well (by my very loose standards), and i regularly shut down the primary air and run on secondary for most of the burn (although I have a square inch or two of leaks around the door supplying a little primary air). Temps above the port measured on the cook top are regularly between 800 and 1,000 F and I can see a very nice chaotic flame fountain for most of the burn. The only modest runaway I had was when I accidentally left the door open for over half the burn, that was when the temps topped 1000 (barely). Still, it was nothing out of control and closing the door and shutting down primary air quickly took the temps back down to the 800-900+ range. How expensive, and what is the learning curve on using a Testo?
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Post by permaculturebob on Dec 9, 2018 9:19:40 GMT -8
I have an old steel Appalachian coal fired water heater. It is shaped like an r2d2 unit (star wars) with a feed opening where it's "mouth" would be and exhaust on the other side of it's head. The whole unit only stood a couple feet tall, about 1 foot diameter, probably 60 years old by now. It had inlet and outlet for water and the jacket was just that top hemisphere (with the two openings of course), a short cylinder below that was the firebox and another section below that for clean out. I used it with wood for quite a long time, set up a thermal siphon loop to a water tank a couple feet away, and depending on the wood quality took two or three loads and a half hr to heat a thirty gallon tank. It's still set up down in the greenhouse, but I'll wait till it stops snowing before venturing down to take pictures.
I thought about sealing the exhaust and feed openings, and actually purchased a 2 foot cylinder extension to provide the height for a riser and planned a 4" j tube rmh for it, I still might.
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Post by permaculturebob on Dec 9, 2018 5:16:34 GMT -8
what about all the glass cooktops like Matt uses? I have one now, and the hottest flames are all over it. does that mean it will one day break, or simply discolor?
They don't seem to break, the surface becomes opaque and feels rough to the touch. I think it's spalling on a tiny scale. Only becomes a problem if you want to see through it clearly. I was just surprised how fast it happens. can it be polished back to clarity?
Would sodium silicate solution applied periodically help protect the glass itself as a preventive, or possibly applied over the spalling to improve visibility?
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Post by permaculturebob on Dec 8, 2018 17:07:04 GMT -8
what about all the glass cooktops like Matt uses? I have one now, and the hottest flames are all over it.
does that mean it will one day break, or simply discolor?
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Post by permaculturebob on Dec 7, 2018 19:12:57 GMT -8
I got the door apart down to some plastic trim and the glass itself. The glass is just a little thicker than 1/8, maybe-- and everything seems so cheap, I'm having trouble believing it could be neoceram, and I did verify that is a trade name for pyroceram. I'm guessing the "heat strengthened" glass is likely not as robust as that. I've sort of put that on the back burner anyway, but when I get a chance I may try and cut it away from as much plastic as possible. Haven't really had a bonfire in ages, all my wood goes into hugel beds.
Heat strengthened sounds a lot like tempered, and I have a double pane oven glass insert that I could try that is likely tempered, and it could be used as is.
Oh, I'm using a visions cookware pot lid, and tonight it cracked, bumping the hot lid against a cold brick I'm not sure if it was the jolt or temperature differential that did it. I used a borosilicate pot lid last year that did sort of explode , then I got a visions fry pan, which lasted a couple months, still ok, but too big for this project. The long handle stays cool, but the pot lid needs an oven mitt after it gets hot.
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Post by permaculturebob on Dec 6, 2018 16:19:03 GMT -8
Seems like I saw a statement by someone on one of these forums that the glass in the doors of microwave ovens is pyroceram ( I think neoceram is also one of the other trade names for it.
When I did a search to try and verify it I could not find any definite answer.
I have a microwave I'm taking apart now, and I'm tempted to just throw it into a bonfire to burn off all the plastic attached to it. I did notice a part number on the door , and later I'll search for it, maybe call the parts dept and see if I can get more specific info.
I also have a couple insulated glass panels out of oven doors, but since those temps don't go beyond 600 I guess they are borosilicate
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Post by permaculturebob on Dec 6, 2018 15:59:13 GMT -8
I can only speak for myself, but this is something I would only use if I had a ready supply of oxygen tanks, and even then I would only use it in an emergency.
Risers lined with ceramic fiber do a much better job at producing the higher temps than a couple inches of vermiculite, and thin stove pipe as the outer shell will last forever.
If i didn't have ceramic fiber (and I didn't for several years) I found that a perlite/clay mix totally outperformed the very first riser I had which was a double walled stainless steel insulated stove pipe. So while it did work, I didn't get my outer barrel glowing cherry red until I started to use the clay perlite riser.
I go by the axiom it is better to keep metal out of the burn chamber and riser
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Post by permaculturebob on Dec 5, 2018 6:06:38 GMT -8
thanks for those reference temperatures, I'm guessing the thought you are transmitting is the CF riser temps could have stayed in that sweet spot between 600 and 900, immediately cooling in the bell to condense the soot. That makes lots of sense, fortunately I took the thing apart after a season with that new riser and didn't continue with the poorly executed batch box design.
even so, I was grateful for the reduced tending time loading the heavier and extra fuel allowed.
I thought the ignition of those secondary gases was closer to 1100F, that explains why I was getting so much secondary combustion in my new dsr with glass cooking top surfaces near 890. Is there a way to infer the internal temps of the top shoebox from the external readings, some sort of expected gradient?
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Post by permaculturebob on Dec 4, 2018 18:29:24 GMT -8
Finally back home to continue tests with the stove, My wood was not great, but I did manage to find some dry oak boards to go with the miscellaneous branches of softer wood, and after numerous attempts finally got the fire started. It maxed out around 850 on the stove top, and the fire fountain was definitely in evidence, although the burn really gets lethargic when I shut down primary air.
I have a ways to go before all the clay is perfectly dry, but it certainly is getting better. Before I left last week the high was around 500 at the stove top.
I read somewhere that the pyroceram actually acts a bit as an insulator, so is it likely that the inside temps are already in excess of 1000 degrees when the outside temps hit 850?
What temps do you think I should expect when it finishes drying out?
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Post by permaculturebob on Nov 30, 2018 6:43:14 GMT -8
The idea that soot is not necessarily a direct correlation with CO is quite interesting. It leads to all sorts of other speculations about other incomplete combustion products. Which ones are most dangerous, in what quantities? My own preference would be soot free, but maybe that's not the best measure of a "clean" burn. I recently disassembled my rocket stove that had a season of use with a batch box, and a ceramic fiber liner to the riser to reduce the diameter to 6inches. Inspection showed the actual diameter had shrunk to more like 5 inches. The ceramic fiber was perfect white, like it had never seen a season of use, but everything outside the riser was covered in soot. I have some ideas about what might have happened, maybe the soot was related to too small a secondary air supply- too large a batch box for the actual riser diameter. Maybe the riser just had gases moving too fast in a venturi for anything to deposit
Maybe something else?
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Post by permaculturebob on Nov 27, 2018 14:06:07 GMT -8
Thanks for the input, the door on the burner box is going to need some retrofitting as well. I was never sure just how hot the oven might get, and if it turns into a simple warming oven I may have to rethink the whole thing. producing hot water is more important than having a baking oven so maybe reworking that space with an insulated outer shell and heat exchanger feeding the water tank is the way to go.
And I need to amend those earlier temp readings, without my glasses I didn't see the scale was changed to F, so the actual temps on the top were around 370 F max--Testing again tonight and I'm already in excess of 420F at the cook top, which I think is in the neighborhood of the temps that ignite wood gas.
Oh, I kept the power vent running all day after the fire went out this morning trying to maximize the drying.
I'll likely do one more fire in the morning, then be gone for a week, so further developments will have to wait.
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Post by permaculturebob on Nov 27, 2018 7:27:16 GMT -8
Anyone that wants to see pics of the build, www.permaculturebob.org/2018/11/26/new-iteration-of-the-old-rocket-stove/Running another fire this morning, temps at the stove top above the port were continuously over 350C until very late in the coaling stage, but I really didn't see much flame through the glass top although I would think with temps that high, there was still a fair amount of combustion going on in the top shoebox. Still lots of moisture coming out of the clay, even some condensation early in the fire inside the burn chamber on the pyrex lid serving as a door .
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Post by permaculturebob on Nov 26, 2018 10:18:12 GMT -8
I finally got my build to the point where I can start to test it. The power vent prevents even a whiff of smoke inside. The part of the bell surrounding the water tank is still pretty sloppy, but I went ahead and roughed it in, sealing cracks with ceramic fiber, and the tank is not plumbed in yet, so the build is far from complete.
My first burn was just a couple small sticks and some paper to make sure I wasn't going to smoke myself out, then this morning I went ahead and stacked some 2 inch branches and lit the thing from the top of the pile and let it start burning .
I don't have glass on the front of the top "shoe box" so I can only see the secondary fire through the opaque top but after closing down the primary air I could see the very beginnings of the secondary burn and after a half hour or so I went outside and put my hand on the exhaust, just warm to the touch, with lots of steam, and the smell test told me there was a fair amount of smoke as well
I used lots of clay and perlite, especially in the top section where it called for insulated fire brick, so I'm hoping the lack of a double rams horn or a fountain through most of the burn is because of the drying process. I'll try and get some pictures online soon.
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Post by permaculturebob on Nov 14, 2018 5:16:06 GMT -8
I'm using a power vent, a fan pulling exhaust out rather than a normal draft and extracting as much heat as I can. The final phase of the extraction is a water tank. At any rate, simply stepping up the vent if necessary would solve that issue if I understand what you're saying.
By the way, I'm a huge fan and thanks for all the work you're doing.
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