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Post by Jura on Jul 31, 2017 4:36:11 GMT -8
A 20 cm system should be able to facilitate 9.4 m² of ISA, combined with a bypass you could easily go a square meter more. But maybe you could ran into trouble concerning the height of the riser. I understand your projected riser is 10 times base figure now, when you revert to 8 times the bell would be smaller or you could fit in the 20 cm system with an 8 times base riser in the existing bell height. All this are the designer's decisions, what can be done versus (or helped with) the wishes of the client. Thank you For all the hints. I'm waiting for the investor's decision as to the bell shape and size. Then I'll decide whether or not to size up to ther 20 cm system with 8xbase sized heat riser Well.... the so called client is the worst kind of client ;-). As it is a close friend of mine and short with budget :-) I'm pondering over the way of constructing and attaching the bypass for the short way to the stack. Any ideas that do not require additional pillars? How about attaching chamotte bricks to the chimney that would poke out of its surface thus allowing to place a sliding damper?
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Post by Jura on Oct 24, 2017 9:10:10 GMT -8
There are two of these openings, remember? Together the size is 400 cm², not quite as much as 1.5 times the chimney's csa but still very adequate. Today is the moment we fired the stove with half loaded firebox for a first time. I'd like to thank you for encouraging and advising me. I removed the additional fundament/ hollowed the space in front of chimney entry to gain the 10 cm of working height And.. to the joy of my faster beating heart the 2,5 m long bench kept warming up like a charm. Herewith I'd also like to confirm there would be no chance for a smokeless start of the cold stove without the bypass (11 deg C, 997 hPa, 8,7m high standard modular insulated ceramic chimney stack)
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Post by peterberg on Oct 24, 2017 11:36:20 GMT -8
I am glad my encouragement helped you through uncertainties. A cold stove isn't the problem most of the time, but a wet stove is... So a bypass comes in handy to get it really dry the first season and may be used for starting the thing first time in fall.
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Post by Jura on Oct 24, 2017 13:46:41 GMT -8
A cold stove isn't the problem most of the time, but a wet stove is... So a bypass comes in handy to get it really dry the first season and may be used for starting the thing first time in fall. I wondered whether it was the issue of the moisture (the plaster hasn't been applied yet) or the cold and high humidity. I must admit I watered the bricks for quite some time before cutting, but the stove has already been ready for a month (we just waited for a corund concrete cast ceiling plates to close it), & even thou the temp range for that period didn't ensure fast drying I hoped most of the moisture had enough time to evaporate. But the white smoke from the chimney (Habemus Papam ;-) ) would indicate otherwise, wouldn't it ? To all interested: The temp range in a white, cast iron oven placed 40 cm above the firebox reached 90 oC after 30 min of burning a load of pine timber construction remainings. (half loaded firebox)
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Post by Jura on Nov 4, 2017 17:24:11 GMT -8
To all interested: The temp range in a white, cast iron oven placed 40 cm above the firebox reached 90 oC after 30 min of burning a load of pine timber construction remainings. (half loaded firebox) UPDATE: Today We burned 2 full batches of the same wood. It was dark so I could't see any smoke from the chimney. But my disappointment was the white oven temp. It again reached 90 deg C only. The oven roof of the oven is situated some 20 cm below the end of the heat riser. When Installed the oven I ordered a higher range thermometer as the original one had scale to 300 C only & due to the heat riser proximity I expected much higher temp. The photo shows the oven placement. BTW. You may see how awful it looks when b l a c k chamotte is used for white bricks. and No, the joints are not that thick, the brick edges were bevelled.
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Post by drooster on Nov 5, 2017 9:19:01 GMT -8
BTW. You may see how awful it looks when b l a c k chamotte is used for white bricks. and No, the joints are not that thick, the brick edges were bevelled. (I can't get the quote to quote properly here) Well I really like the dark mortar and pale bricks ... looks good.
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Post by Jura on Nov 5, 2017 11:02:32 GMT -8
BTW. You may see how awful it looks when b l a c k chamotte is used for white bricks. and No, the joints are not that thick, the brick edges were bevelled. (I can't get the quote to quote properly here) Well I really like the dark mortar and pale bricks ... looks good. Well.. de gustibus non est disputandum. Fortunately.. the stove was to be plastered anyway. But during brick laying when you touch the brick it has a fingerprints all over and .. by an unfamiliar onlooker it may be perceived as a .. sloppiness Any thoughts on why the temp in the oven remains so low?
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grga
Junior Member
Posts: 76
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Post by grga on Nov 6, 2017 4:13:04 GMT -8
Is your white oven made from brick or metal? I guess the placement is wrong, should be as high as possible (over the riser) or on the batchbox ceiling. The first I tried end reach max 200deg. The second I didn't so far but according to member Dvavolk it is also not good (http://donkey32.proboards.com/thread/2276/project-batchbox-180mm-brickwork-bench?page=9). Also black oven is not a good enough solution according to member rakettimuurari: donkey32.proboards.com/thread/2308/brick-sidewinder-riser-baking-oven?page=1&scrollTo=24875 i have similar experiences as rakettimuurari with my rocket pizza: donkey32.proboards.com/thread/2257/show-rocket-pizza-ovenwhich does not get hot enough floor temperature... and gets cold soon after burning. So I would probably skip the white oven idea in my current heater work and bake directly in the core cca. 1 hour or more after the burning (if I decided )... However if i build one it will be connected to the top of the batchbox
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Post by Orange on Nov 6, 2017 4:16:06 GMT -8
Jura where're from? What are the building materials for the riser, firebox, oven? Can you post more pictures or skp?
My guess is all that massive chamotte bricks eat up the heat.
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Post by pinhead on Nov 6, 2017 6:11:29 GMT -8
You have a white oven within a bell.
The large volume of the bell works in the bell's favor, allowing the stratification of gasses within - which causes the temperature to drop as elevation within the bell drops.
To make an oven work within a bell, the oven would have to be at the very highest point of the bell. I would personally build the base of the bell with firebrick and place it directly above the heat riser...
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Post by Jura on Nov 6, 2017 15:03:05 GMT -8
Is your white oven made from brick or metal? I guess the placement is wrong, should be as high as possible (over the riser) or on the batchbox ceiling. The first I tried end reach max 200deg. The second I didn't so far but according to member Dvavolk it is also not good (http://donkey32.proboards.com/thread/2276/project-batchbox-180mm-brickwork-bench?page=9). Also black oven is not a good enough solution according to member rakettimuurari: donkey32.proboards.com/thread/2308/brick-sidewinder-riser-baking-oven?page=1&scrollTo=24875 i have similar experiences as rakettimuurari with my rocket pizza: donkey32.proboards.com/thread/2257/show-rocket-pizza-ovenwhich does not get hot enough floor temperature... and gets cold soon after burning. So I would probably skip the white oven idea in my current heater work and bake directly in the core cca. 1 hour or more after the burning (if I decided )... However if i build one it will be connected to the top of the batchbox Thanks for your effort with the links. The oven is a cast iron one, with no any bricks around and I was afraid to place it higher because of temps, and usability. It wouldn't be handy to use it having it placed 20 cm above your head. Mind I have my core 50 cm elevated from the floor level I have been following Klemen with his build and bothering him from the very beginning about the white oven temp. But unfortunately the owners haven't fired the stove till the moment I had to place the white oven. I decided for that placement height as I saw this it having been applied in other rocket stoves. I even placed a photo of a friend of mine who claimed the range of 250 oC is easily reachable. I took it as guaranteed especially that we talk about temps of 1000 oC at the end of heat riser. Yea! I'd also skip it if I were to start building it now. I feel more and more inclined to place a K-thermocouple as rhinokeegan did in his built
You have a white oven within a bell. The large volume of the bell works in the bell's favor, allowing the stratification of gasses within - which causes the temperature to drop as elevation within the bell drops. To make an oven work within a bell, the oven would have to be at the very highest point of the bell. I would personally build the base of the bell with firebrick and place it directly above the heat riser... Ugh! I was afraid of such position as Peter warned me even about placing a cast iron bypass at the height of heat riser. Moreover it my core is elevated for 50 cm from the floor level so the riser ends at 1,9 m. It would require using stool as the owner is pretty short. Anyway the top of the oven is almost leveled with heat riser end. Therefore I'm so surprised about the temps being so low. in my next built I'm definitely going to place the white oven (if any) above the heat riser. Jura where're from? What are the building materials for the riser, firebox, oven? Can you post more pictures or skp? My guess is all that massive chamotte bricks eat up the heat. I'm based in the south of Poland. The riser is a octagonal one. Made of high quality chamotte and insulated with a 2,5 cm wool. The same with firebox The oven is a cast iron one. The bricks used for the wall are also chamotte one. but it is a special kind of chamotte used in a metal factory kilns. I'll post more photos once I'm back home (no access to the files @ the moment) I hope the stove owner agrees to sharing the *.skp file Well I was sure this kind of brick has enormous heat capacity but..As I understand it's about garnering temp by a highly conductive material as cast iron.. so I was almost sure it would reach the desired range..
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Post by satamax on Nov 6, 2017 20:23:06 GMT -8
Well, if this can save your but. You could try cutting the base of the oven and replace it with a grid. Not too many problems with fly ash.
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Post by Jura on Nov 7, 2017 3:59:54 GMT -8
Well, if this can save your but. You could try cutting the base of the oven and replace it with a grid. Not too many problems with fly ash. Thanks. The owner wished to have a white oven so as not to have a fire smelling cakes. So ...do you find this temp range at that height normal ?
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Post by pinhead on Nov 7, 2017 5:05:41 GMT -8
You have a white oven within a bell. The large volume of the bell works in the bell's favor, allowing the stratification of gasses within - which causes the temperature to drop as elevation within the bell drops. To make an oven work within a bell, the oven would have to be at the very highest point of the bell. I would personally build the base of the bell with firebrick and place it directly above the heat riser... Ugh! I was afraid of such position as Peter warned me even about placing a cast iron bypass at the height of heat riser. Moreover it my core is elevated for 50 cm from the floor level so the riser ends at 1,9 m. It would require using stool as the owner is pretty short. Anyway the top of the oven is almost leveled with heat riser end. Therefore I'm so surprised about the temps being so low. in my next built I'm definitely going to place the white oven (if any) above the heat riser. Don't forget the effect volume has on temperature and the difference between heat and temperature. "Heat" is a measurement of the amount of energy within a substance. "Temperature" is a measurement of the "density" of heat, i.e. the amount of that energy confined in a space. The more heat in a particular volume, the higher the temperature. Following that, as there is a finite amount of heat exiting the riser, the temperature drops as the gasses expands into the bell. This is in addition to the heat being dissipated by its cooler surroundings. If you were to place an oven one foot above the riser inside an volume the size of a steel barrel it would be entirely too hot. However, placing that same oven that same distance above the riser within a larger volume, the temperature will be lower.
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Post by Jura on Nov 7, 2017 6:08:59 GMT -8
Don't forget the effect volume has on temperature and the difference between heat and temperature. "Heat" is a measurement of the amount of energy within a substance. "Temperature" is a measurement of the "density" of heat, i.e. the amount of that energy confined in a space. The more heat in a particular volume, the higher the temperature. Following that, as there is a finite amount of heat exiting the riser, the temperature drops as the gasses expands into the bell. This is in addition to the heat being dissipated by its cooler surroundings. If you were to place an oven one foot above the riser inside an volume the size of a steel barrel it would be entirely too hot. However, placing that same oven that same distance above the riser within a larger volume, the temperature will be lower. I believe the every single forum member should read the above sentences. I just hoped the ~43 kWh would be enough to warm up a little bit ISA undersized bell and the air heated will have enough energy to bang the white oven surface and would not dissipate that fast. Anyway! if I have enough time and the owners will be willing I'm going to place a K-thermocouple thermometer right below the ceiling some 20 cm aside of the heat riser.
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