iau461
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Posts: 60
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Post by iau461 on Sept 13, 2023 22:37:07 GMT -8
Another idea we are playing with: We are thinking about making an open source guidebook for the DSR3 build. In collaboration with you of course. We think we found a way to make these stoves in an easy and affordable way, pretty low tech and with most of the materials everybody can easily source.... Sieger De Vrijlemerij Hello Sieger, If you don't mind, a few questions from the USA. My core is built and tested, need to finalize my bell/bench design. 1) In your first DSR3 build, the bell and bench appear to be single wall, made with oversize clay brick, finished with a thin layer of clay over fiberglass stucco netting. Has the owner had any issues with the skin of the bell cracking? Would you still build a bell that way? 2) The more recent see-through with U-shape bench build appears to have a 2-wall bell, the inner wall made with firebrick slabs (not cheap!), the outer wall of large clay brick, and an expansion gap between the two. Was that done for better durability/less cracking, heat retention, or both? 3) What material(s) are you using for the bell ceiling? I've scoured your many great pics but can't tell. An open source guidebook would be wonderful! Thanks again, Craig |
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Post by skywalker on Sept 14, 2023 11:10:44 GMT -8
Another idea we are playing with: We are thinking about making an open source guidebook for the DSR3 build. In collaboration with you of course. We think we found a way to make these stoves in an easy and affordable way, pretty low tech and with most of the materials everybody can easily source.... Sieger De Vrijlemerij Hello Sieger, If you don't mind, a few questions from the USA. My core is built and tested, need to finalize my bell/bench design. 1) In your first DSR3 build, the bell and bench appear to be single wall, made with oversize clay brick, finished with a thin layer of clay over fiberglass stucco netting. Has the owner had any issues with the skin of the bell cracking? Would you still build a bell that way? Hi Craig, here's a quick response: The bell is not entirely single wall. From the bottom till just 20 cm below the exit of the top firebox it's made with adobe bricks. On top of that it's build with split fire bricks on the sides and split adobe bricks. So the top part of the bell has a liner of fire bricks. It's inspired by the Mallorca build by Peter van den Berg. Check out this video: www.youtube.com/watch?v=Yo5lBIcx_8U&embeds_referring_euri=https%3A%2F%2Fbatchrocket.eu%2F&feature=emb_imp_woytThe stove is build this way to prevent it from becoming too heavy. The floor of this house was not strong enough for a full size mass heater like the see through stove you saw. In this case you won't have any issues with cracking. 2) The more recent see-through with U-shape bench build appears to have a 2-wall bell, the inner wall made with firebrick slabs (not cheap!), the outer wall of large clay brick, and an expansion gap between the two. Was that done for better durability/less cracking, heat retention, or both? This stove is build with more mass for a beter heat retention. That's the only reason to use more stones. There are nog signs of cracking. 3)What material(s) are you using for the bell ceiling? I've scoured your many great pics but can't tell. We've build the ceiling just like in the Mallorca build. Check out the video and you will be surprised by the simpleness. Good luck with your build, very curious about the results. An open source guidebook would be wonderful! Thanks again, Craig |
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iau461
Junior Member
Posts: 60
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Post by iau461 on Sept 18, 2023 13:34:15 GMT -8
It's inspired by the Mallorca build by Peter van den Berg... This stove is build with more mass for a beter heat retention... We've build the ceiling just like in the Mallorca build. Check out the video and you will be surprised by the simpleness... Good luck with your build, very curious about the results. Perfect, thanks! I had seen still pics of the Mallorca build but missed the video. One more question: is your mortar simply screened clay, or do you mix it (2/1?) with sand, or...? |
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iau461
Junior Member
Posts: 60
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Post by iau461 on Sept 21, 2023 8:44:41 GMT -8
I believe someone posted a link to a SketchUp drawing of a DSR3 airframe/door. But I can't find it now. Pointers?
I believe the intake vents totaled 50% of system size CSA.
Thanks for any help,
Craig
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Post by peterberg on Sept 21, 2023 11:37:18 GMT -8
I believe someone posted a link to a SketchUp drawing of a DSR3 airframe/door. But I can't find it now. Pointers? I believe the intake vents totaled 50% of system size CSA. Yes, that file is probably this one: go to pberg0.home.xs4all.nl/pictures/dev2021/ the file is DSR3coreinch.skp or DSR3core150.skp The complete link is redirecting to the same page as it was on. Hopefully this is a workaround. |
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iau461
Junior Member
Posts: 60
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Post by iau461 on Sept 21, 2023 16:38:54 GMT -8
I believe someone posted a link to a SketchUp drawing of a DSR3 airframe/door. But I can't find it now. Pointers? I believe the intake vents totaled 50% of system size CSA. Yes, that file is probably this one: go to pberg0.home.xs4all.nl/pictures/dev2021/ the file is DSR3coreinch.skp or DSR3core150.skp The complete link is redirecting to the same page as it was on. Hopefully this is a workaround. Thanks, Peter. I had that link, just forgot about it, and didn't realize it was your latest/final door. I'll incorporate something like that into my final stand/door design. For anyone who cares to look or comment, my SketchUp is at app.sketchup.com/share/tc/northAmerica/hQCcliOYEJg?stoken=GIKqW-CBkoWCrTAn245A12_lR4GR9At06Hq0A4DeK-HoGrgKdg-GYpOgKwR1um1w&source=web . A few explanatory notes: 1) It's a double layer bell, primarily red brick on the inside, a 1/4" air layer, then about 4" of adobe/cob (colored orange). 2) I didn't draw the bell ceiling, but it will be like the Mallorca build, maybe a bit thinner. Angle iron (1.5 x 1.5 x .25" thick) supporting a layer of insulating firebrick splits (1.25" thick), topped with a layer of Superwool, a layer of regular red brick, and SuperWool in the gaps all around. 3) the flue is external to the bell. I can't draw curved pipe but I think you'll get the idea. There's a bypass partway up the bell that will have an external shutoff valve, normally kept closed. 4) The sitting bench to the left of the bell is passively heated. 5) The large "bed bench" to the left of the sitting bench is more than large enough to accommodate a queen sized mattress. Son and wife plan to use it accordingly. If you hide the stone layer on top, you can see the initial plan for heating it. Intention is to have a thermocouple measuring flue gas temp, and if/when it gets high enough, a fan will kick on that draws warm air into the bed bench, and pushes cooled air back to the bottom of the core through the long 6" duct. If it turns out there is enough heat available (high flue temps, even when the bed bench fan is on), then we'll put in more ductwork and fill the bed bench with more mass (soil). If anything is drop dead stupid/wrong, please let me know. :-) Thanks. Craig |
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Post by peterberg on Sept 22, 2023 1:51:06 GMT -8
This would be a new way to fed a bench. Interesting how this'll work out in the long run.
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iau461
Junior Member
Posts: 60
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Post by iau461 on Sept 22, 2023 18:47:40 GMT -8
Apologies in advance Peter, I just want to be 100% sure before I pay someone to fabricate a door / frame:
Your drawing is for a 150mm / ~5.1" system, with a system CSA of about 20.4 square inches.
The intake vent at the bottom of your doorframe has a CSA of 11.6 square inches, or about 57% of system CSA.
The 4 supply vents inside your doorframe total about 12.8 square inches, or about 63% of system CSA.
Should I stay close to that? For some reason I was expecting 50% for both of those CSAs, same as the firebox port.
Whatever your answer I'm going to suggest to April Wickes that she incorporate it into her most excellent spreadsheet.
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Post by peterberg on Sept 23, 2023 2:02:28 GMT -8
Apologies in advance Peter, I just want to be 100% sure before I pay someone to fabricate a door / frame: Your drawing is for a 150mm / ~5.1" system, with a system CSA of about 20.4 square inches. Please don't apologise, there's a mistake I spotted so it's good to ask. There are two drawings: one in imperial and one in metrics. The metric one is a 150 mm system indeed, but it's equivalent in imperial is 27.4 sq". So, the rest of the parts' csa is quite different compared to reality. To begin with, the opening in the door frame could be in the front. I measured both the prototype and the development model (both still in one piece, thankfully) The front opening in both is 48% of system csa, proportion 1 to 4, not accidentally the same as the firebox port. The csa of the rectangular ducts left and right of the door together is 30% of system csa. The 4 supply vents in the door frame together are about 50% again. There might be some slack in these numbers, but the target has been specified as 50%, 30%, 50%. There's another detail that might be overlooked: the front opening is leading into a box that is the same csa as both the left and right doorposts together. So that is 60% csa both left and right, resulting in less friction in the feed trajectory of the air. Since it need to go through 90 degrees to both sides and 90 degrees up again, I provided for lots of room. The net result is low air velocity entering the doorframe, higher velocity in the doorframe itself and low velocity again to enter the firebox. The air supply in the basic batchrocket is just 25%, due to the fact that it needs to be regulated this way. The DSR3 is completely different in this respect. The proportions further down the system are done in such a way that it is very reluctant to get to a higher combustion rate than the capacity of the afterburner. That's why the air inlet is designed as one that is oversized and open or closed, nothing in between. I really, really like this feature. |
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iau461
Junior Member
Posts: 60
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Post by iau461 on Sept 23, 2023 10:21:58 GMT -8
Glad I asked! I wasn't thinking about the CSA of the frame members themselves, only the vents, and this requires much bigger frame members than I had in mind.
My 8" system has a CSA of about 50.3". If I understand you correctly:
The 2 vertical frame members should have an internal CSA of about 50.3 x 30% = 15.1 square inches each. Square steel, 4 x 4 x 1/16" thick, would be 3.875" square internally, or 15.0 CSA. Close enough I'm guessing. And I believe I should use the same size for the top horizontal member.
The bottom horizontal member of the frame should be about twice that CSA. 4 x 8 x 1/16" thick would have a CSA of about 30.5 square inches. Also close enough.
There are 4 supply vents: one in each vertical frame member, and 2 in the top horizontal frame member. Total need to be ~50% of CSA, so each vent could be 12.5% x 50.3 = ~6.3 square inches, so 1 x 6.6" should work.
Sound correct?
I like the idea of your open/closed front air inlet door too. Serves as a total shutoff of the system, to prevent unnecessary heat loss up the flue between burns.
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Post by peterberg on Sept 23, 2023 13:22:56 GMT -8
Yes, correct. The 4x8" bottom member could be made out of two U-profiles welded together.
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iau461
Junior Member
Posts: 60
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Post by iau461 on Oct 6, 2023 6:18:20 GMT -8
Yes, correct. The 4x8" bottom member could be made out of two U-profiles welded together. Peter, after further review I think I/we must have miscalculated. Looking at the Loam Freemanship builds, as well as your own DSR3core inch.skp drawing, it seems clear that a frame made with 2x4" side members, and a 4x4" bottom member, would be sufficient for an 8" system. This is my current baseline: The intake vent under the bottom member will be 3x12", about 71% of system CSA. The sum of the two vertical frame sides equals about 32% of system CSA. The sum of the four supply vents into the firebox will be about 60% of system CSA. |
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iau461
Junior Member
Posts: 60
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Post by iau461 on Oct 6, 2023 6:41:52 GMT -8
Here's some photos of the build of my two benches, one small and passively heated for sitting, and a large actively heated one that can have a mattress on top of it. Dry stacked concrete block with surface bonding mortar.  Beginning layout of fan and ducts.  After completing duct work and top skin support. Skin will be Pennsylvania bluestone (2 pieces shown).  View of the ductwork.  The large actively heated bench will next be packed with a clay/sand mix. |
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iau461
Junior Member
Posts: 60
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Post by iau461 on Oct 6, 2023 22:05:23 GMT -8
Pic of the Arduino minicomputer that will monitor temperatures and turn on the fan to heat the large ducted bench when the flue temp gets high enough.  Closeup of LCD, 3 thermocouples, and relay to turn fan on/off. Besides the flue, I plan to monitor temeratures inside the bell, at the top and about halfway down.  |
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iau461
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Posts: 60
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Post by iau461 on Oct 7, 2023 13:19:09 GMT -8
The first mockup of my flue and bypass.  A couple quick questions, maybe for Peter if he happens to see this: 1) In this photo, the flue intake (bottom of the ell) is only about 2 inches off the floor. I believe you said somewhere that you recommend at least 1/2 system size, or 4 inches above the floor? 2) An easy alternative for the intake would be to bring the bottom horizontal pipe into the bell at floor level, and eliminate the ell. Letting exhaust gas flow directly into the horizontal pipe. Is this a bad idea, due to heat stratification, i.e. temperature differential from floor level vs. 8 inches above? |
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