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Post by patamos on Jan 8, 2015 13:54:26 GMT -8
Hi Folks, I'm getting down to the design details on a 6" batchbox system. The primary purpose is to heat about 700sq.ft of a basement suite. The metal flues and chimney are pre-existing, so 6" is the max diameter. The available footprint is about 3' x 5' nestled into an interior wall niche (4' x 6' i.d.). I am thinking of a tallish tower to offer lots of radiating surface into the main room, with a small bench to the side. Something akin to the overall shape and design of Robert's last build in Poland. The difference being i want to batch feed the oven from underneath rather than a j-feed from the side. So this has me wondering what modifications might be in order to ensure i get even heat to the oven. I see Robert has a refractory slab a few inches above the heat riser, and has situated the oven in the bell above with 8" of space to the sides and 12" above. Given the higher firing temps of a batchbox, can anyone suggest how best to modify this arrangement? Also, considering the relatively intense blast of heat that the 6" batchbox offers... i have been revisiting in my mind the idea of pre-charging/firing a black oven with 3 or 4 inches of mass and having that serve as the ISA of the bell. It would be less idiot-proof, but would spare the cost of building/buying a cast iron oven. Feel free to talk me out of this idea. ![:-/]( ":-/") Back to the white oven idea. As an alternative to the cast iron oven, the folks i am building for have an old mild steel wood stove, and i am pondering the idea of using that as a white oven. My concern here being that the thinner metal body would be more prone to uneven heat delivery... and eventually become unstable. Many thanks to everyone who contributes to this amazing forum. I look forward to reading any and all suggestions. pat |
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Post by matthewwalker on Jan 8, 2015 17:07:57 GMT -8
I think the black oven idea is cool but in practice would be full of fly ash and sorta dirty after a while.
I would probably try to do a masonry oven situated generally over the riser with flow around it to the downdraft section. Don't ask me how, it's a rough idea. But, yeah.
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Post by patamos on Jan 8, 2015 17:38:57 GMT -8
Hey Matt, Thanks man. Always good to hear your take on things  That is a good nail in the coffin of the black oven idea... Been reviewing Robert's thread about his J bell oven build. Looks like he came up with some good solutions there. peace |
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Post by Daryl on Jan 9, 2015 4:21:19 GMT -8
From a cooking standpoint, it may be counterproductive to build a black oven with a rocket indoors. The point of having a rocket is efficiency and a component of cooking with fire is the smoke factor. A full blown black oven rocket would be best outdoors.
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Post by patamos on Jan 9, 2015 13:37:28 GMT -8
Hi Daryl,
thanks for your take on things
Ya, i hear you.
I've been contemplating how well a 6" batchbox could pre-fire a small black oven. Then once the fire is out start baking with the flywheel heat.
All in all though, it is probably more trouble than it is worth...
peace
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Post by DCish on Jan 12, 2015 7:00:34 GMT -8
I know that Satamax has posted pictures of baking things in the residual heat of the firebox. Peterberg says dense refractory is fine for the burn chamber of a batch box, so you might be able to build a batch with baking in mind...
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Post by Robert on Jan 12, 2015 10:46:19 GMT -8
Been reviewing Robert's thread about his J bell oven build. Looks like he came up with some good solutions there. peace Dear Patamos... I need to make a good review in that post, since now the heater is tested... The oven in that build not working... The piece of firebrick i put above the riser completely robbed the oven of temperature... while having a big fire maybe in an oven tere will be 180C... when finished maybe 120C... This is not an oven temps at all... I would say that this is a some sort of a disater... If i would be doing it again, for sure without the firebrick above the riser... i would let the heat hit the bottom of the oven directly... Recenty i am building also stoves according to Kuznetsov design... I was at ten days workshop with him and it was very interesting... Now i can see that the ceramic black oven is really nice idea... Having some fly ash inside is not a problem for me... After i finish the fire in my stove i have 350C in the oven... 12 hours later in the nmorning it is 100C... This is what i call an oven:) I would suggest to your build to make a black ceramic oven. i make a quick drawing... just an idea what i mean. maybe it helps... of course this is the core... than you have to build around it in a bell manner of course. BTW. did you learn how to use Sketchup?  |
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Post by patamos on Jan 13, 2015 15:15:24 GMT -8
Hi DCish, Thanks for that. Ya, i have spoken with the clients about such a possibility. They could go that way, but are hoping to get a bigger roasting pan in there. Something closer to 14" x 14" I have been considering also Vortex's style of heater which has a firebox close to those dimensions... I do wonder though, to what degree there would be a trade off between mass and insulation. For example, if they want enough flywheel to slow roast a ham over 3 or 4 hours, would i have to thicken up the box's walls to a point that significantly compromises its warm up time? Hi Robert Good to hear from you. Sorry to hear about that oven not working.  At the very least, you have learned something valuable that is being shared with many interested builders. Is there any way to get in there and take out the firebrick above the riser? If you were doing the same oven again, would you also make the bell around the oven closer to the oven walls? I really appreciate your kindness and curiosity, and i very much respect the way you have been seeking, learning and experimenting. Now you have me wondering about the black oven again !?!?! If ceramic black oven, how thick does Kunetsov make the castings? For how big a fire? I know you are busy learning a million things, but i would love to hear whatever you care to share. Am i learning sketch up? Funny i just committed to learning it so i can send some plans to the building authorities, and i discovered my 6 year old Mac OSX computer cannot run the 2014 Sketch Up program. So, for now i am still out of the loop. Hey, another question: Whatever became of the Joris style side load oven you built with the ceramic glass top? I am very interested in learning more about this design possibility also. Do you know if he is okay with people sharing his techniques? well being pat |
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Post by DCish on Jan 14, 2015 9:20:40 GMT -8
As for thickness and insulation I'm afraid I'll have to defer to more knowledgeable others. Robert's black oven concept sure looks cool!
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Post by patamos on Jan 15, 2015 10:38:36 GMT -8
Ya, getting the oven's flywheel dialed is what really intrigues me these days.
We'll be burning mostly soft woods, 2nd growth doug fir, hemlock, and punky spruce 2by framing off-cuts. So i anticipate no more than 20kw per single full load.
This output might be something akin to a small to mid-size kachelofen, so i am starting to take a closer look at their numbers and techniques for optimizing heat delivery to the bake oven
I've been imaging various ways to route the exhaust gasses through and or around the bake oven. I see a lot of the black ovens have a rectangular throat on the floor, oriented front to back, and then a rectangular exit up top oriented side to side nearer the front opening. This location could be to make sure a bit more heat gets into the front areas of mass to compensate for loss through the door. Just a guess. Maybe it is also to keep the glass in the door clear ?
Anyway, if i go for a black oven with a rectangular throat in the floor then i'm thinking i had best make that at least 1.5 system size. Exit could be forward top with flue gasses coursing through narrow runs/chambers around the outsides and back of the oven. Then dropping down into a bench bell along side the tower.
All musings welcome...
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Post by Robert on Jan 15, 2015 15:23:53 GMT -8
Hi Robert Good to hear from you. Sorry to hear about that oven not working. At the very least, you have learned something valuable that is being shared with many interested builders. Is there any way to get in there and take out the firebrick above the riser? If you were doing the same oven again, would you also make the bell around the oven closer to the oven walls? Hi Pat. no worry with an oven... that is actually a fault of a client who insisted to make that protection over the riser. i was against, since the cast iron can be treated with the direct fire... anyway, he insisted and he is using an oven for drying... and to keep food warm... once we made apples with cinnamon and risins...was nice... for melting a cheese on a piece of bread is also good. if i would make it again, than just without the protection, but now after some experience with ceramic ovens i think if anyone wants a real oven for baking, it has to be a black oven... and if made properly, doesnt have to be black at all:) mine it is clean now after receiving high temps... and you know after 12 hours it is still 100C inside... so on one burn i can make veggies and in the morning heat my breakfast. I really appreciate your kindness and curiosity, and i very much respect the way you have been seeking, learning and experimenting. Now you have me wondering about the black oven again !?!?! If ceramic black oven, how thick does Kunetsov make the castings? For how big a fire? I know you are busy learning a million things, but i would love to hear whatever you care to share. yes... ceramic black oven!!!! with kuznetsov usually we build it from firebrick... in Europe 6,5cm... usually firebox is for 6-8 kg of wood... whole heater gets hot, and oven stays really hot for 12 hours. i am more and more interested in the "classic" masonry heaters and fireboxes that offer clean burn... once i would like to build a few and test them and see results... Lars Helbro claims to have 92% eff in his simple firebox of Gymse heater... same 92% goes with the batchbox with p-channell... so where is the difference i am starting to wonder... One kuznetsov heater was tested in Sweden and they claim it has 95% overall thermall efficiency... oh so many things to learn... I remember one thing i learned from Peter and Lars and actually Igor Kuznetsov as well... all of them kept repeating: KEEP IT SIMPLE:) Am i learning sketch up? Funny i just committed to learning it so i can send some plans to the building authorities, and i discovered my 6 year old Mac OSX computer cannot run the 2014 Sketch Up program. So, for now i am still out of the loop. Hey, another question: Whatever became of the Joris style side load oven you built with the ceramic glass top? I am very interested in learning more about this design possibility also. Do you know if he is okay with people sharing his techniques? well being pat Learn damn sketchup!!! older versions should run it smooth on your gear...and it is so easy to share ideas and designs than. Joris style is actually very simple... I am quite sure that he is ok with sharing. He has wonderfull spirit of sharing... He learned from our beloved Peter, and now he is sharing with others...Oh if only Sjang would have that spirit too:) Anyway i am still going to use that secondary air since it is so obvious and it is being used in so many other fireboxes that simple cannot be patented:) regarding few ideas on a black ceramic oven maybe this could be a help. three heaters build by Boris Kukojl in US. picasaweb.google.com/100099482278258044258Cheers my friend. |
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Post by patamos on Jan 20, 2015 22:55:52 GMT -8
Phew. new hard drive, new operating system… reloading various applications… finally into sketch up. Ya my interest began with double flue grundofens. My friend Holgar Laerad studued in the Weimar with a fellow named Ekhart Bruell who had been commissioned to rebuild many of the very old ones in that region. Eventually i got to build one with Holgar For a large house and where one can place a decent footing, i too like the traditional approaches - masonry heater firebox, bypass flue and big bells of some shape or another. A Kutsenov M heater achieving 95% efficiency? Is this using the same parameters as Peter regarding ballast gasses? All in all i see the 6" batch box rockets filling much the same niche as the lighter weight kachelofens. I don't recall how many kg of soft wood can fit in the box, but it is no doubt much less than 8kilos. Still, i sense a somewhat high mass black oven could have enough flywheel for most baking purposes. For stovetop/griddle emphasis and a low mass black or white oven i see a j-feed working well. The trouble is, around here, most people have metal box stoves with 6" flues. And a 6" J-feed is not going to offer a lot of space heating without a lot of feeding. Such is the case for this next build/reno, so i am gravitating towards a 6" matchbox system. Robert, further back in this thread you showed a sketch of a blue coloured stove. Is the input into the black oven from the heat riser at the rear and exit ports near the front on the sides… something you have tried with this size system? And, from there i wonder how thick to make the oven walls before switching to insulation. Lotsa questions and ideas floating around my head at this stage Any and all thoughts are welcome... thanks pat |
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Post by esbjornaneer on Dec 2, 2015 10:15:04 GMT -8
Hi Pat did you get around to making this stove? I have not got around to posting the build of my first rocket yet as I would like to test it first and am away from home for a month...
I have however started researching options for an outdoor cob oven type pizza/bread/etc oven and one of the ideas I have is how would it work with a bell inside a bell?
I think it would be easier to build the bells with bricks(fire/adobe) than with loose cob. The idea I have is sort of pictured in this image (www.pinterest.com/pin/334392341058061122/) but instead of having the cool gasses from the 2nd bell traversing the top of the 1st (and hence cooling it), the 2nd bell would enclose the 1st and vent from below the 1st bells floor. That way the 1st bell would be heated from both inside & outside.
Do you think that would give more heat and/or flywheel effect for a 1st bell black oven?
I also thought that the inner (1st) bell would be able to have thicker walls (or need shorter firing time) as heated from both sides than a standard cob oven that is only heated from the inside of the 'bell'.
The engine (8"-J or 6"-batch) would naturally need to be placed under the 1st bell and by what I have just read from Robert it would be better to have the heat riser venting straight onto a fire brick floor than to have a deflector before the floor.
As my primary reason for this system is cooking I would insulate the 2nd bell, but for space heating purposes I would not and instead have slightly shorter flywheel cooking time. But as I understand it it is possible to cook in a rocket black oven while firing it if the temps are right for what you are wanting to bake.
Any thoughts on my idea are welcome, and if they help others too all the better.
In peace, Esbjorn
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Post by patamos on Dec 2, 2015 21:56:54 GMT -8
That bell within a bell is an interesting idea  I have never done it but imagine the inner dome would heat up quite quickly. You could have the exit from the first bell down low along one side, then the exit from the second bell low over on the other side. This could be a great way to harvest much heat in a small area... |
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Post by patamos on Dec 4, 2015 0:01:35 GMT -8
Hi Esbjo,
to answer your question. I ended up building a vortex instead. See thread 'vortex variant'
but for heaters with a big emphasis on oven cooking i can see coming back this way to a batch box or vortex with oven above. If the latter maybe a bypass damper to send excess heat into a nearby harvesting mass.
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At the very least, you have learned something valuable that is being shared with many interested builders. Is there any way to get in there and take out the firebrick above the riser? If you were doing the same oven again, would you also make the bell around the oven closer to the oven walls?
