JBW
New Member
Posts: 16
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Post by JBW on Jan 11, 2013 15:08:41 GMT -8
Sounds like powder coat, not paint. If it's that tough, it might hold up to the barrel temps without burning off.  |
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Post by satamax on Jan 13, 2013 9:22:04 GMT -8
Sounds like powder coat, not paint. If it's that tough, it might hold up to the barrel temps without burning off. It doesn't on top at least, and stinks! |
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dvawolk
Full Member
DSR2 125mm open system (actual project)
Posts: 271
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Post by dvawolk on Jan 15, 2013 15:13:41 GMT -8
After reading this thread (man the info here is sooo great - i severely lack of sleeping in these days!) i picked some bits that would maybe come together nicely for my usage... I am thinking of using horizontal batch stove maid with firebricks: (peter's sketch)Bricks in our country are in size of 10"x5"x2.5"(25x12.5x6.2cm) or 10"x5"x1.25"(25x12.5x3.1cm) so it would probably be better to simplify the thing for building with these block (for me) rather than stubbornly folowing the exact sizes. There is one thing i am not sure of: how powerful system should i have? The one sketched with bricks is 6 incher. That would surely be more than enough for me. I have an outside insulated apartment with not so good windows, winter temperatures can go to -15°C for a week or so sometimes but usually not below -5°C. The area to be heated is about 50 sq. metres. Storing heat? Hm. Satamax idea with available concrete blocks for bells is very tempting for a quick and easy construction. I can get square concrete manholes with 5cm (2") wall thickness in (inner sizes): 40x40x37cm (height), 100kilos 50x50x47cm (height), 148kilos  The above have the ceiling closed (opened only on one side, so perfect for the top) The belove are opened above and below: 40x40x45cm (height), 85kilos 50x50x55cm (height), 120kilos  In english it is called concrete manhole. Prefered option is the smaller version because of easier lifting.Two bells? maximum height 2metres. I would put part of a stove into lowest concrete part - as much as it could come in. Would the concrete blocks be able to tolerate the heat in a first bell? I would also add mass over them (cob?) to store more heat and to dissipate it for a longer time. Oh and the stove will be connected to an existing chimney (schamotte flue with 20cm diameter). The chimney is built inside a house. I would like to store as much of a heat as possible. If i understood part of this thread: the batch stove can be used without doors and without p-channel OR with doors and p-channel? Please, what would you suggest for batchbox size/heat storage/system? 6inch? is it too much for me? With proper heat storage? Peter? Max? Klemen |
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Post by peterberg on Jan 16, 2013 2:34:30 GMT -8
Bricks in our country are in size of 10"x5"x2.5"(25x12.5x6.2cm) or 10"x5"x1.25"(25x12.5x3.1cm) so it would probably be better to simplify the thing for building with these block (for me) rather than stubbornly folowing the exact sizes. Klemen, Indeed, it would be better to use the bricks as is. I'll try to make a new sketch based on your brick format. As a side note, it would be better to have the riser as a square as opposed to a rectangle. There is one thing i am not sure of: how powerful system should i have? The one sketched with bricks is 6 incher. That would surely be more than enough for me. I would think the 6 incher is the right size. Keep in mind it's not necessary to fire the stove all day and besides that, half or quarter loads will do just as well. So save the full load for depth of winter. Would the concrete blocks be able to tolerate the heat in a first bell? I would also add mass over them (cob?) to store more heat and to dissipate it for a longer time. I'm sorry to say, these concrete manholes won't tolerate the heat directly over the riser. As a rule of thumb, the farther away from the riser, the cheaper materials you are able to use. These concrete parts are fine around the firebox and riser, but not above it. The construction of the top half of the first bell has to be out of refractory materials such as the fire brick you mention. Of course, a 2nd bell could be made entirely out of these manholes. Cob could be used to make the walls thicker, provided you'll use straw in it or a stucco net. Chimney as mentioned would be close to perfect. If i understood part of this thread: the batch stove can be used without doors and without p-channel OR with doors and p-channel? That's correct, provided you have to block half of the firebox opening probably, depending on the quality of the chimney. Equipped with a p-channel the running of these stoves is more reliable, Ill have to add. Where in the world are you located? |
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Post by peterberg on Jan 16, 2013 4:13:24 GMT -8
Klemen, Here's a sketch of the batch box core adapted to your brick format. A square riser will be on a par with a round riser, when the diameter of the circle is equal to one side of the square. The port is adjusted for that assumption. |
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morticcio
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"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
Posts: 371
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Post by morticcio on Jan 16, 2013 8:01:05 GMT -8
Peter,
I'm looking to convert my test 8" vertical feed RMH into a horizontal feed one. Could you confirm if the dimensions below for an 8" system are correct please?
Burn chamber
Height - 436mm (17½")
Width - 290mm (11½")
Length - 580mm (23")
P Channel (h x w) - 2.4mm x 6.5mm 24mm x 65mm (1" x 2½")
Gap between burn chamber and riser (h x w) - 336mm x 6.5mm 65mm (13¼" x 2½")
Do you have a Sketchup model for an 8", similar to the one you did for Klemen please? I'm using standard 9" x 4" x 3" bricks with a 7" square riser (49in² csa).
Many thanks,
Andy
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Post by satamax on Jan 16, 2013 8:28:17 GMT -8
Peter, i'd bet Klemen is from Germany. ;D For writing schamote  |
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dvawolk
Full Member
DSR2 125mm open system (actual project)
Posts: 271
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Post by dvawolk on Jan 16, 2013 10:17:51 GMT -8
Raise your bets!
Max, Peter, i am two countries lower from Germany and i se sunrise just before Italians :-). I am from Slovenia!
Morticcio, i think P chanel is in centimetres...
Peter, many thanks for the sketch! And for other info.
I didn't mention that the chimney flue is 12m high - that won't be too much problem if the outgoing temperature is not too low.
I calculated the inner area /without floor of the bells to be used.
Somewhere before you said that 8" (20cm) RMH can take about 5sq. metres of bell's surface (3/4 surface of 10metres of tubes is 4,7 sq.metres in 8")
If i say that my 6"(15cm) RMH sistem can have 8 metres of tubes:
0,15m* PI*8m *3/4 =2,8 square metres. You said somewhere before that the bells can take a bit more of a surface, so 3 sq. metres will be okay? Surface will be about 3/4 concrete and 1/4 firebrick (upper part of first bell). But this is a batchbox, horizontal feed. It is more powerful at 6" than ordinary RMH. Will it need more inner surface?
So even though that my sqare riser has 15,8x15,8=250sq.cm C.S.A., later in the sistem i can still use 15cm (6") diameter tubes (C.S.A.=177sq.cm) for connecting the bells and chimney? Is using 15cm tubes still optimal here?
Thank you, much. Now i go sketching :-) wohooo!
Klemen
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Post by peterberg on Jan 16, 2013 12:15:31 GMT -8
Do you have a Sketchup model for an 8", similar to the one you did for Klemen please? I'm using standard 9" x 4" x 3" bricks with a 7" square riser (49in² csa). Morticio, I'd recalculate your numbers and they are correct. Even down to the maximum 4" above the port. The 7" square riser has got the same capacity as a round duct with a diameter equal to one side of the square. The only error is in the port numbers, but Klemen pointed that out already. And yes, I could do another sketch, based on your brick size. Would you please give me the measurements in millimeters? That's much, much easier for me. |
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Post by peterberg on Jan 16, 2013 12:43:06 GMT -8
But this is a batchbox, horizontal feed. It is more powerful at 6" than ordinary RMH. Will it need more inner surface? Yes. I'd think it's quite some time ago I calculated this surface numbers. Not for the batch box rocket, anyway. So it's a little bit different nowadays. My prototype do consist of two 55 gallon barrels, stacked on top of each other. These come down to 3.5 m2 of thin steel wall, which isn't even enough in some circumstances. I honestly don't know what the difference to a brick wall is in taking up heat, but I'd reckon about twice as slow. So you'd better to calculate for 7 square meters (75.3 sq ft.), total surface area of the bell(s), not counting the floor. This an educated ques, no proof yet, so don't hassle me when it isn't the correct figure. So even though that my square riser has 15,8x15,8=250sq.cm C.S.A., later in the system i can still use 15cm (6") diameter tubes (C.S.A.=177sq.cm) for connecting the bells and chimney? Is using 15cm tubes still optimal here? Yes, it is. The square duct is less efficient in transporting gases as compared to the round one. Mind you, when you are going from square to round, you have to make the transition as smooth as possible. A lot of RMH's using a square or rectangle cross section for the feed tube and the tunnel could be running into problems when using a round riser with the same csa as the square.  Of course, this my own opinion, everybody is entitled to think otherwise as they like. |
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morticcio
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"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
Posts: 371
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Post by morticcio on Jan 16, 2013 13:42:20 GMT -8
I think P chanel is in centimetres... Edited :-) Would you please give me the measurements in millimeters? Many thanks Peter... Firebrick dimensions: 230mm x 114mm x 76mm |
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Post by peterberg on Jan 17, 2013 4:49:25 GMT -8
Morticcio, Here's your 7.4" batch box rocket stove, adapted to your fire brick size. The riser is slightly larger, closer to a real 8" round duct equivalent. All the layers are grouped, it's possible to extract them one by one. The p-channel duct has been thought of as 70x30 mm, some dimensions of the brick assembly are slightly different from yours. |
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dvawolk
Full Member
DSR2 125mm open system (actual project)
Posts: 271
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Post by dvawolk on Jan 17, 2013 4:51:14 GMT -8
Hi, again. I did a sketch to implement brick version of batchbox rocket.  . SKP file attached! It's not a masterpiece but i think it is basically okay! I sketched two bells. The first has about 5sq. metres and the second has about 1.1 sq. metres (floors excluded and i with removed 0.5 sq.m for the rocket stove that is near the bell's wall). The upper half of the first bell is from firebricks. Else is from concrete and covered with cob (brown). Of course, the first bell will be closed in the end :-) The rocket stove and the bottom part of heat riser will be insulated. I have a few concerns: are connections between the bells and the chimney okay? (those are sketched but inner dimensions are true) Is it okay that this rocket version has only 75cm high heat riser measured from the top of the gap? (compared to previous brick model it is 22cm lower) The total inner working surface is about 6.1 sq.m. I was thinking of putting a small metal oven insert (WxHxD=30x22x40cm) into the upper third of the first bell. Would it function well? Because of the oven i sketched only 6.1 sq.m instead of 7sq. m as Peter suggested. How high temperatures should i expect by the chimney entrance with this kind of system? Regards, Klemen Attachments:
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Post by peterberg on Jan 17, 2013 5:55:02 GMT -8
I have a few concerns: are connections between the bells and the chimney okay? They are OK, but only just. A little bit wider would be better, I'd think. Please install some clean-out ports, a lot of the ash will settle on the floor of the bell. The bell connection won't plug up easily, because of the higher gas velocity in there. Is it okay that this rocket version has only 75cm high heat riser measured from the top of the gap? Yes, this is correct. My current prototype is even shorter, sporting an insulated riser, I must add. Insulating the firebox isn't that important, the whole of the riser is. The total inner working surface is about 6.1 sq.m. I was thinking of putting a small metal oven insert (WxHxD=30x22x40cm) into the upper third of the first bell. Would it function well? Following my own assumption, the heat capacity of the steel oven is twice as much. The oven is about 0.5 sq. m., so calculating 1 sq.m. for the oven is correct. How high temperatures should i expect by the chimney entrance with this kind of system? Should be about 100 to 120 C. (210 to 250 F.). When the stove is still wet, it's very handy to have a bypass somewhere. After the running in is done you don't need it anymore. In case you don't want to install one, install a larger clean-out port close to the chimney floor. You are able then to prime the chimney with a small fire. Handy for sweeping the chimney as well. This is a very interesting project, more masonry heater than rocket stove. I will be very pleased when you could publish the proceedings complete with pictures and the occasional video. |
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morticcio
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"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
Posts: 371
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Post by morticcio on Jan 17, 2013 6:00:34 GMT -8
Morticcio, Here's your batch box rocket stove adapted to your fire brick size. Many thanks Peter. Will update with progress as and when. |
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