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Post by fasardi on Apr 22, 2019 6:39:49 GMT -8
Hi! i´m trying to decide between building a BBR8 or a DSR2-8, but i have a limited space, and to have a good view of the fire (a little luxury perhaps) i´m thinking on having the door on the side of the fire box (if i build the DSR2, the BBR could be a sidewinder). Will it be very crazy? i´m thinking it could work if the door is in not in the bottom, but maybe the wood can fall and brake the window... i guess it won`t be the best and i´m complicating something than could be easy An another cuestion, maybe replied earlyer in the thread (14 pages and still running) is the DSR2 as efficient as the BBR? I saw the Testo analiced burns and seems to be, but i don´t have real experience in the matter. Thanks a lot!
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Post by peterberg on Apr 22, 2019 12:44:02 GMT -8
As far as I can see, the DSR2 could also be built as a sidewinder, but it would be more complicated than the straight one. I love simplicity, a large part of my efforts are spent on that. A door in the side of the firebox is a lame compromise in my opinion, whether it be BBR or DSR2.
The diagrams of the DRS2 shows a slightly lower overall efficiency as compared to the best BBR test runs. All due to the higher temperature of the exhaust gases of the development model. During years of batchrocket development efficiency went up quite a number of times. Mainly due to better combustion and in some cases due to lower exhaust temperatures. Better defined bell sizing is one of the reasons, thanks to Klemen Urbanja. I fully expect this will happen to the DSR2 design as well.
Development of the DSR2 started only about six months ago, this is an extremely short period. Efficiency, quality of combustion and stability of the burn are very, very good already. All this is possible because there's much more experience with combustion and bell constructions since 2012.
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Post by fasardi on Apr 22, 2019 15:32:25 GMT -8
Thanks for your help Peterberg. Yes the idea of the lateral door seems complicated and not very useful. Trying to complicate things again, I was wondering if I could add a bench to the DSR2. I said I have very little room, and I'm trying to have something than will remain heating during the night. My concern is than the flue will have to go down after leaving the core to get into the bench. I know that bells are more effective than benches, but really need the inertia, and don't have room to do heavy bell. I have just enough room right now to make a 2 meters bench, next year I'll add another room and could add another bench or a bell
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Post by peterberg on Apr 23, 2019 8:08:49 GMT -8
Trying to complicate things again, I was wondering if I could add a bench to the DSR2. I said I have very little room, and I'm trying to have something than will remain heating during the night. My concern is than the flue will have to go down after leaving the core to get into the bench. A bench is very well possible but forget about a piped bench, think about a bell bench instead. There should be no flue that's leaving the core, just a small(ish) bell above and around the core. This bell could also be a steel barrel. A bell bench is a hollow space where the exhaust opening to the vertical chimney flue is lower than half of the height inside. Since it's a bell construction the exhaust could be anywhere around the perimeter.
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Post by fasardi on Apr 23, 2019 8:21:56 GMT -8
I have very little place and i think i´wont have enough intertia with the little mass i can get in a bell in that space. Thanks Peter for your help, since i have zero experience building stoves (or building walls...), have little time spare and the winter just around the corner, i guess i´ll get professional help. I´m already in touch with someone, but this forum is really a very good place for getting info and at least now i know what i need and how could it be achieved! I´ll post photos when the construction begins, and pay attention to learn every step.
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Post by coastalrocketeer on Apr 23, 2019 9:44:52 GMT -8
Fasardi- you can use halved 55 gallon barrels to create a bell in a bench size area and build up the same cob and rubble over/around them as with ducts. The real requirement is a minimum of 4.5x system CSA so that gasses can slow and stratify inside the bench. At least I think this can work with the batch box rocket heaters... Certainly a “bell bench” has been done with J tubes after the metal barrel that provides immediate radiant heat. (That barrel could be covered with cob or masonry to make it thermal mass as well as far as I know) You would need SOME kind of chamber/passage from over the top box to carry the gasses down to your bench, and possibly a bypass of some sort to heat the chimney at startup... peterberg - do my thoughts above concur with your experiekce and what you have seen others do with batch box cores that worked?
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Post by coastalrocketeer on Apr 23, 2019 9:51:20 GMT -8
Also, do you have photos or a drawing of your intended space and any fixed constraints such as chimney location that may exist? That may help with suggestions as to how to lay things out and how to design your heat extraction bench setup.
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Post by fasardi on Apr 24, 2019 7:18:03 GMT -8
Also, do you have photos or a drawing of your intended space and any fixed constraints such as chimney location that may exist? That may help with suggestions as to how to lay things out and how to design your heat extraction bench setup. Thanks for your help.
I`m having a little economic crisis here (if you watch Argentinian news you´ll find out it´s been a couple of rough years) so i`ll have to put the proyect to a hold for some time... and use lots of warm clothing. But i`m expecting some financing in a couple of months, enough to close a little room of 2.25 m x 2.25 m and planning on doing there the stove. Since it´s in a side of the house, i`m thinking in heating a water thermal battery (saw the post about it and love the idea) and using it to make a radiant wall system. Hopefully i`ll have enough cash to do it. BUT i don`t know how to size the stove, if i use the batchrocket.eu calculator i`ll need a 250 mm system (it´s really cold outside, and in some years the house will be bigger). The roof in that room wouldn`t be tall enough to place a normal BBR10 and a water tank in top of it, but maybe a can make a bell in a side with the tank inside of it, or a DSR2 with the tank on top. Any thoughts? Plus, i was wondering if a normal 55 gallon/200 litres barrell will do the trick, or if it wont handle the heat well in time...
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Post by coastalrocketeer on Apr 24, 2019 8:27:17 GMT -8
With water in it a 55 gallon drum will definitely be fine heat wise. You will likely have to replace it periodically due to it rusting from the water.
I am planning to use 55 gallon barrels as radiators in various locations in my house. Filled with 50 gallons of water, each one will represent 450lbs of thermal mass in the room it is in.
Since they will be easily replaceable I am not so worried about longetivity for these.
If you use one as your primary heated tank, you will want to make sure it can be replaced every 2-3 years, or when it starts to leak, without much trouble.
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Post by fasardi on Apr 24, 2019 15:33:29 GMT -8
With water in it a 55 gallon drum will definitely be fine heat wise. You will likely have to replace it periodically due to it rusting from the water. I am planning to use 55 gallon barrels as radiators in various locations in my house. Filled with 50 gallons of water, each one will represent 450lbs of thermal mass in the room it is in. Since they will be easily replaceable I am not so worried about longetivity for these. If you use one as your primary heated tank, you will want to make sure it can be replaced every 2-3 years, or when it starts to leak, without much trouble. Thank you, I'll have that in mind. If I could I'll get a used water heater tank or something like that, but still have a way to change it. Do you think the tank inside a bell will work well at a side of the stove?
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Post by travis on Apr 25, 2019 17:02:06 GMT -8
I would say Peter is definitely a professional and his advice is very solid. Go with him if at all possible. As for the mass of a bell not being enough but wanting a bench for better thermal inertia through the night, I would think you would be dealing with a bench that’s heavier than a bell. You can also do a double skin brick bell which would give a very nice amount of heat storage through the night. I live in Mongolia and use a bell with the old “bell” heating wall, this does very well. I use the old radiator system that was here as well in my house and it works fairly well(not great because the stove gives heat off before it is given to to the radiators). This uses an old metal radiator inside the stove to be the heat transfer element, which seems good. Not sure about a large tank, this might cool the exhaust too much until the water is warm and stall the draft any time the system is cold.
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Post by fasardi on Apr 26, 2019 3:36:17 GMT -8
I use the old radiator system that was here as well in my house and it works fairly well(not great because the stove gives heat off before it is given to to the radiators). This uses an old metal radiator inside the stove to be the heat transfer element, which seems good. Not sure about a large tank, this might cool the exhaust too much until the water is warm and stall the draft any time the system is cold. Thanks for your input. I´ve thought of it, really seem easier than having a big tank inside a bell, plus it would be easier to change the tank when it rust. I was thinking on how to make a big door in a bell and don´t see an easy solution in a bell than will be inside a house. Maybe just a radiator or a copper coil in the top of the bell will work just fine. But I was thinking, when the system is cold, wouldn`t be the same a cold water tank than a cold heavy bell? Plus i`m cheking if there is any way to move the water inside the house without a pump, because there are plenty of electrical cuts in the winter. I was aiming to do a radiant wall system, but than the pipes will have to be thinner than a radiator system, and in that case i think a pump will be needed.
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Post by travis on Apr 26, 2019 3:59:14 GMT -8
True you do need a pump. And the thing I see is combining a cold bell and cold water but you could also make the bell have less internal surface area and factor in the water.
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Post by fasardi on Apr 26, 2019 4:49:37 GMT -8
Yes, maybe i´ll try that, or two bells with a bypass, one with the water tank. I searched at the "open thermosyphon" thread and someone said in Kazajstan they use a system without pumps. The problem is than you need to put the heated water tank in the bottom of the system, and an opened buffer tank in the top off it.
I`ll try to make a test outside system and see if i can make it work, because my house has two floors, and i think than will be a lot of preassure to handle safely.
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Post by coastalrocketeer on Apr 26, 2019 9:43:02 GMT -8
In my outdoor “open tank topped bell” system I will deal with draft issues with a chimney bypass at the top of my bell that is variable by an exterior handle.
Cold starts would presumably be with full bypass, and as the bell warms, I expect to be able to turn it fully off, but want to be able to open it just a crack to orovide draft as needed it it turns out heat extraction exceeds the output of my core.. The tanks will only be in the top 1/4 of my bell, height wise, and below that will be filled with brake rotors and other scrap steel for additional thermal mass, so I may wind up making three exits, with one at the top of the bell, one a chimney diameter below the bottom of the tank, and one at the bottom for charging the full mass.
Since it’s all going to be outdoors, smoke-back is not the hazard or nuisance it could be indoors... and I expect it will take some time to figure out what the best way to operate it is, with the core I initially use.
I am making the core section a “doghouse” extension off of the metal shed that will house the bell and tank setup and it’s exterior insulation, and my initial core will be a cylindrical DSR (not a peterberg combustion analyzer tested design, so I do not advise following me in that unless you like experimenting)
I will be optimizing it based on observational evidence to hopefully perform similarly to Peter’s DSR II design currently being fleshed out. In any case, t will be easily replaceable with a cast DSR II once that design becomes finalized. And if I find my bell and tank setup just need a larger system CSA to match the bell that can be decided before casting my DSR.
I am hopeful that some Ideas that thread has given me about multiple zones of direction change and pressure change in the combustion path will allow me to optimize the cylindrical DSR concept to perform similarly.
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