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Post by Robert on Nov 29, 2013 16:36:13 GMT -8
Dear rocketiers. After few ordinary rocket mass heaters it is time to go further. Now i am amazed by the bell kind of idea, so i would like to make my first Bell kind of a stove. And to make it more exciting I would like also to bake bread in the stove, so i wish to add an oven to it. So simply the goal is to make the J-tube bell stove with an oven and a small heated bench to warm the butt on. The main goal is to heat the room, but an oven is also a must to have feature. It is going to be a 6incher with the exhaust pipe of a 160cm diameter. The only problem is that i never did the bell stoves before, also adding an oven is a new feature for me. So i would like to ask you all more experienced rocketiers to kindly help me, and share some experience and guide me in the process. So here it is just the basic idea i have. Please tell me if this is a good directions to go. The main core comes on the left. Heat from the heat riser heats the bottom of an oven. The flues go from the first chimney (C1) to the second bell, which is the area of an oven. Then through the second chimney (C2) goes out. The arch is where the door will be for an oven. I am wondering if it affect the working of a stove if a door will not be super airtight? So what do you think about that idea? Thank you very much for your help.
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Post by ronyon on Nov 29, 2013 17:29:53 GMT -8
Seems like the top of C1 should be above the inlet of C2, by a little bit. As for the door, if you build the oven as a "white oven", and keep the flue gasses separate from the food/door, you could have any old door. Much safer. I would use a large stainless steel pot or barrel with the lid made into the door.
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Post by satamax on Nov 30, 2013 0:48:53 GMT -8
Robert, as i see it, you might have smokeback problems. If the floor of the oven heats faster than the gases comming from C1.
As ronyon says, do a white oven, it's simpler. And since the gases from a rocket don't smell of smoke, and sometimes are real noxious, i don't see the point of having a black oven. Xept for faster heat.
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Post by Robert on Nov 30, 2013 1:59:19 GMT -8
Thank you for your comments. Actually i was thinking about the "black" oven to be sure it will heat enough for baking purpose. But if you suggest that it could make some problems, than i am ready to change the concept. Most likely i will be doing it few times after your advices. It will be an oven for the client, so i will have to use a really nice components, and minimalize any possible problems. I could use this kind of an oven, but tis is made from a thick steel, so i need to be sure that the temperature will be hot enough. Maybe the better idea is to have one bell kind of a stove and not make the division for two chambers? This stove which was made by Dragon Heaters inspires me in my efforts. What i am considering also is how to place the oven in a chamber so it will be supported well. Thanx for your help. Robert
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radek
Junior Member
Posts: 94
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Post by radek on Nov 30, 2013 4:27:43 GMT -8
hi Robert I guess one main bell with the white oven in it and than small bench would be much better way .The question will be how hight should the white oven be located in the bell so its not too hot or too cool.
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Post by satamax on Nov 30, 2013 5:36:41 GMT -8
I would place the oven within "top gap" distance above the heat riser, and use a nice thick refractory slab for the bottom of the oven. Two RSJ across the bell to hold it. Then few refractory bricks for the sides, and another slab for the top (or a cast dome, or pre made brick arch, whatever takes your fancy) One good thing, you can leave the oven open for more heat when not in use.
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Post by Robert on Nov 30, 2013 6:31:22 GMT -8
Hey Satamax. Is there any possibility you could make some drawings? Since my english is not so perfect i have a difficulties with understanding exactly what you are writing What the "top gap" means... RSJ? And if you say about keeping the oven open, that means we speak about the "white" oven?
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Post by satamax on Nov 30, 2013 11:58:28 GMT -8
Dobje Robert.
Post your sketchup drawings as atachements here, i will then be able to modify them, easier than starting from the ground.
RSJ, rolled steel joist, an I beam
Top gap, the gap which is usualy between the top of the heat riser and the top of the barrel. 1 to 4 inches in general. I wonder if putting a refractory slab too close to the output of the heat riser, might crack it.
Yep, i'm talking about a white oven. Baking wise, exept if you want a pizza oven, i don't see the the point of using a black oven.
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Post by Robert on Dec 4, 2013 14:47:04 GMT -8
Ok. I been thinking for a while. According to Radek`s advice i have modified the design a little bit. it is going to be a one bell stove. I was thinking on how to support the oven also, and i think i will be using a refractory slab... It is on the pictures, i hope it will be strong enough. I am intersted about the RSJ idea of yours satamax, so if you could elaborate on that would be nice. Here is some pictures of a new design. There are also two doors. One for clean out, and the other for starting the initial draft. I want to be sure that the stove will have no smoke back issue. Do you think it is a good idea to make this doors? So here are the pictures: and also the sketchup file with the sketch. later i will be publishing the whole design for the bricks dimension that we have in Poland. bell-oven sketch.skp (143.66 KB) So here comes the question. Should i use fire bricks for the bell, or normal fired clay brick will be fine?
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Post by peterberg on Dec 5, 2013 9:37:32 GMT -8
Robert, I would think you should use fire bricks, at least for the top half.
But maybe this bell system is overly large for a 6" rocket to drive. How do you know the size of the bell is just right? I would say this type of rocket would be able to drive a single bell of about 4 m2 (43 sq ft) internal surface area excluding the floor.
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Post by Robert on Dec 5, 2013 10:18:34 GMT -8
Hmmm. Thanx Peter, actually i was not measuring this befor, being quite sure it is ok. But when I added all surfaces now i get 7sq/m. Do you think it might be too much? And how do you find the concrete slab idea for the support of an oven? Do you have another suggestion maybe? And another question. Do you think that the small doors for starting the draft is a good idea... I just want to be sure there will be no problems with starting the stove, so i figure it out that making it possible to preheat the exhaust pipe will be a good idea. Thanx for helping in the process of design guys. This is my first bell type of a stove
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Post by satamax on Dec 5, 2013 10:54:20 GMT -8
Robert, here's what i had envisioned. The RSJ are shy of the walls, about 1.5 or 2cm so when they expand they don't wreck the walls. Sitting on brick corbels. One thing about sketchup, please, do triple clicks and make components, it's far easier to modify afterwards modifiedbelloven.skp (143.48 KB)
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Post by peterberg on Dec 5, 2013 11:12:28 GMT -8
But when I added all surfaces now i get 7sq/m. Do you think it might be too much? Way too much, even a 6" batch box rocket would be too small for that much area. And how do you find the concrete slab idea for the support of an oven? Do you have another suggestion maybe? One way to implement an oven support is by building a column of bricks, two of them layed flat in every layer. This will add to the internal surface area, but it will also contrubute to the mass of the bell. And another question. Do you think that the small doors for starting the draft is a good idea... I just want to be sure there will be no problems with starting the stove, so i figure it out that making it possible to preheat the exhaust pipe will be a good idea. In general, this is a good idea. Especially handy when the stove is just built and you need to drive the moist out. One remark though about the feed tube. Isn't that one a bit high compared to the riser? One way to calculate the parts is to do the measurements in the heart of each channel. Feed tube from top to halfway down the height of the tunnel, the tunnel from the middle of the feed to the middle of the riser, the riser from the heart of the tunnel to the top. Usually, the tunnel is the one that will dictate the length because it has to go through the stove's wall. Size ratio is feed : tunnel : riser = 1 : 2 : 4 according to this method.
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Post by Robert on Dec 5, 2013 13:33:15 GMT -8
Thank you guys for your comments. This is the picture of the changes that Satamax has made: I love the idea of the RSJ steel beam for the support of the oven. I am thinking that actually just one beam should be enough... The oven is 50cm deep... front of the oven will be supported on the bricks of the front face of the stove... so i thing just the support on the end of the oven will be enough... oven it self weights 30kg and it is made of cast iron... so one beam should be enough what do you think? The other changes is that the oven is moved just above the heat riser to the center. It is to help distribute the heat more even as i suppose? I also was thinking about so if you think it is "necessary" than i rather move the feed tube to the front, to have the heat riser and oven centered in the stove. Another change is that the heat riser was made higher. Just very close to the oven. I am not sure if this is necessery... When i was visiting Peter (hurray!!!) i have seen that the temperature on the exit of the heat riser was 550C... i think it is a lot, and do not need to be so close to the oven. it will burn things inside i think. What are your thought about that? And now few words of advice from Peter i would like to understand very good, so i will repeat, and please correct me if i am wrong. So i should make it smaller then? I remember when we spoke you told me that the safe area is 5,5 to 6 sq/meter... is that right? I am a litle bit confused since i read somwhere something like this: "The System has the following advantages over forced gas movement systems: Unbelievable flexibility of design, allowing creating stoves of almost any shape and size. In comparison with limited length and shape of channels in forced movement systems, there are virtually no limitations here." www.stovemaster.com/html_en/designsysadvs.htmlseems like there is the limitation to the size? I was thinking about building the column, but i quit that idea, since i wanted to keep it more simple (according to teh KISS principle you told me about). Just want to understand it really good. If i put the column inside i will have to add all of it surface area to the ISA of the stove??? And if this column will be inside of the bell so will i really feel the heat radiation? Yes it might be... the core with the riser was not scaled yet since this is just the sketch of the general idea... later i will make it correct to the size, and with the dimension of the bricks. Thank you for reminding the formula. Thanks to all of you who can add something to the design. I feel great support from all of you experienced builders.
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Post by satamax on Dec 5, 2013 15:40:33 GMT -8
Robert, i would put a refractory plate at the bottom of the oven, and put it within barrel gap distance. Otherwise i think it would be too cold. There's one thing i'm wondering, insulate the top of the oven or not? Dunno! If it's cast iron, whatever heat you apply to it will be radiated back into the bell if it's any cooler than the oven. A good idea to implement, may be shortening the heat riser, and having a deflector above it, which would let the flames out of the heat riser hit the bottom of the oven or not. Let say 4 inch between the heat riser and oven, and the deflector being two inches away from each of theses. Robert, remember that RSJ are fragile with heat. so they need to be far bigger than if they were suporting the same weight in cold conditions.
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