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I'm getting ready to build my wood oven and the info overload is making me nuts!  RSS feed

 
Posts: 41
Location: Hiroshima-shi, Japan
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HI! Save ME! Please.

I'm putting together a small cafe in Japan and I need a wood oven for bread and pizza etc.. It needs to be a little bigger than regular pizza oven as it will serve other functions in a public venue. My initial thought was it needed to be brick in order to meet scale requirements.. but then I remember large clay ovens in Peru that seemed to be fine.. My guess so far is i should go for something around 48" interior diameter... this is assuming a bread oven where the fire is on the same hearth surface as the foods... I'm, as stated, losing my mind trying to streamline this into a final design and would love to know how others have solved this. I'm considering a.. anything that will work really. I'd like to be able to build it without needing to ship parts from Europe or USA.

1. How about a mix of clay and brick?? How big of a clay dome can I make? Is 48" rounded dome structurally doable?
2. My understanding is that dome shapes are much better than barrel for even heat dispersion.
3. I need a door big enough for bread and for baking dishes/pans
4. Making this a sort of hybrid rocket oven has also crossed my mind... thoughts? How best to do such a thing?


Thanks!!

I gotta get moving for now, I hope somebody waves a magic wand on this oven puzzle!

B
 
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Posts: 2580
Location: Upstate NY, zone 5
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I'm not an authority on wood-fired ovens (I have built one so far), but I think the first thing to figure out would be the usage pattern you need. A traditional oven has the fire inside, heats up, the fire is raked out and baking begins, with fast foods to start and slow foods later. If you want more even usage, a rocket-fired oven might be better, as it can be kept at relatively constant temps all day after warming up.

I don't know the fuel consumption differences between styles, but I tend to think you could use less wood with a rocket oven. Mine is an L-tube beneath the oven floor which splits into five channels (more than necessary, I found) and comes up around the edges of the chamber. I have the equivalent of two bricks thickness of floor between the fire channels and top surface; it would heat up much faster with only one brick thickness. I have a chimney above the door opening which draws nicely, and if it were inside a building and going high enough to clear the roof, it could probably keep negative pressure at the door so hot gases (no smoke after the first five minutes of firing) don't come out when the door is open.

48" doesn't sound too big for a cob dome as long as it is well supported. If there is a tension ring around the outside base to prevent any spreading, the dome might even have good earthquake resistance.
 
Brendan Edwards
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Location: Hiroshima-shi, Japan
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Your description sounds somewhat like what I was thinking.. like a feeder tube system... is yours just a network of brick channels underneath the hearth or what? can you give me a quick sketch? Yours sounds scalable which I wasn't sure of being able to do easily with the Pompeii brick oven for instance. What are the dimensions of your feed tube, channels and exhaust approx? I guess for this size I would make a fairly thick clay dome with perhaps a brick base to support it.. steel strap ring for tension?

thanks!

to admin who posted vid link... You figure the vids will solve these issues pretty roundly?
 
Glenn Herbert
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The oven is about 27" diameter plus 9" more or less to the door. Dome and door heights are proportional per Kiko Denzer's book Build Your Own Earth Oven.

The L-tube is nominal 6" diameter, with the horizontal section about 3" deeper and V-bottomed, where a channel to supply air to the back could go (I don't think this one needs that, as it burns hot and clean as is.) The horizontal leg is about 24" total, and the vertical is about 30" to the top of the splitter chamber where it goes in all four directions. From there it branches so as to heat as much of the floor as possible from below, with the channels being on the order of 4" diameter +-. Sorry I can't locate pictures of the actual channels now.
dragonoven-02.jpg
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drylaid stone base with cavity for L-tube
dragonoven-05.jpg
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oven floor temporarily placed for fitting
dragonoven-06.jpg
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looking down one of the partially completed channels to the splitter and top of riser
dragonoven-07.jpg
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first test, burning out the L-tube forms
dragonoven-08.jpg
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sand form before 9" chimney chamber extension
dragonoven-finishing.jpg
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putting some finishing touches on the outside
dragonbread.jpg
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dragon bread!
 
Brendan Edwards
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Location: Hiroshima-shi, Japan
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thanks for sharing your thoughts, it helped me get closer to how to proceed.
 
Opportunity is missed by most people because it is dressed in overalls and looks like work - Edison. Tiny ad:
five days of natural building (wofati and cob) and rocket cooktop oct 8-12, 2018
https://permies.com/t/92034/permaculture-projects/days-natural-building-wofati-cob
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