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Rocket bread oven in existing BBQ-site with salvaged oven

 
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Hi fellow permies.

I decided to build a bread oven in an existing BBQ-site, using firebricks for the core and a salvaged electric oven as the oven part.

Here's a video of the first burn after dry stacking the J-Tube:

No smoke, I was quite content.
I then tried to make the whole setup a bit smaller and stacked it again, this time using the energy to cook some lentil soup.

I'll keep adding to this post as the construction continues.
1_BBQ-House.jpg
a clay barbeque with a dry stack rocket core in front of it
2_Insulated-base.jpg
Using expanded clay, bound with lime
Using expanded clay, bound with lime
3_Oven-dissasembly.jpg
I stripped it of all electric parts. It's basically a metal box with insulation now
I stripped it of all electric parts. It's basically a metal box with insulation now
4_Plastered-BBQ.jpg
the plastered barbecue
5_Dry-Stack.jpg
A short drystack rocket core
5a_Smaller-Burntunnel.jpg
[Thumbnail for 5a_Smaller-Burntunnel.jpg]
6_First-cooking.jpg
water in a pot being heated on a j tube rocket core
7_Half-brick-base.jpg
[Thumbnail for 7_Half-brick-base.jpg]
8_Burn-tunnel.jpg
[Thumbnail for 8_Burn-tunnel.jpg]
9_Burn-tunnel-insulated.jpg
[Thumbnail for 9_Burn-tunnel-insulated.jpg]
10_Burn-tunnel-insulated_with-Cobb.jpg
[Thumbnail for 10_Burn-tunnel-insulated_with-Cobb.jpg]
 
Benjamin Dinkel
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It's done! Had a trial run yesterday and it worked quite well (after an incident with resin rich pine )

Now I'm reviving the sour dough and really eager to start baking.

Also a little bit of cob work, maybe plastering left.

Any questions, feel free to ask!
11_riser-built.jpg
[Thumbnail for 11_riser-built.jpg]
12_riser-insulated.jpg
[Thumbnail for 12_riser-insulated.jpg]
13_oven-assembly.jpg
[Thumbnail for 13_oven-assembly.jpg]
14_oven-installed.jpg
[Thumbnail for 14_oven-installed.jpg]
 
gardener
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Location: Cincinnati, Ohio,Price Hill 45205
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forest garden trees urban
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Benjamin, I love what you're doing there!
Do you have a deflector plate or any mass inside the oven?
 
Benjamin Dinkel
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Hey William,
thanks a lot!
I put a "pizza stone" in there. A 35cm x 35 cm tile of refractory material. It seals in the back, as to not let the hot gases short circuit.
It worked quite well, though I hope to get a higher temperature once the whole cob etc has dried out.

Tonight we're having a pizza party!

IMG_20240613_205801.jpg
Pizza stone with trial flat bread
Pizza stone with trial flat bread
 
Benjamin Dinkel
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Pizza party was a great success. We made 12 pizzas in total, taking between 3-5 minutes per pizza. We used 1,5 buckets of wood for it, the fire got very hot. I am really pleased with it.
270D74AB-ADE6-4B52-A847-7D184A6CDF29.jpeg
pizza in a black rocket oven
 
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I find this build very inspiring.  I had a smallish electric oven that mounted in a wall cabinet that no longer functioned that I was considering doing something like this with.  Unfortunately, it was destroyed in the process of removing it from the wall.   So much for my plan!  But your results clearly show that an oven can be repurposed in this way with very good results.  It is a white oven, and I think that is a big plus.  Have you thought about putting a thermometer on it?
Thanks for sharing!
 
William Bronson
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Wait, is it a white oven?
I thought the gasses hit the bottom of the refractory tile and streamed up and around it before exiting out the back.

This electric ovens does seem to consist of inner and outer steel boxes, with insulation in between the two.
Perhaps you could make  a white oven by removing the insulation layer and running hot gasses through the emptied space.
 
Benjamin Dinkel
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William,
it is a black oven (the only white thing about it is the outside). You describe the way it works perfectly.
And yes, the electric ovens are basically 2 metal boxes with some insulation in between. I wouldn't use them to make a white oven but rather stick to the true and tested white rocket oven made from 2 oil barrels.

Thomas,
thank you for your kind words.
Sorry to hear about your oven being destroyed. I got this one from a second hand store for 7€. I'm sure you could find one for free or very cheap at a junk yard, as you basically only need the structure and it doesn't have to work.
Yesterday the thermometer arrived in the mail. I'll update you about the temperatures next bake.
I made some bread the other day and it was done quicker than in my conventional oven, so I expect over 250°C (480 F).

 
Thomas Tipton
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Benjamin.  I see I misunderstood the part of it being a black oven.  But isn't it true that by removing the insulation and directing the flue gases around the outer oven shell, the oven will still heat up, though perhaps more slowly?  That had been my plan.  To direct the post-riser flue gases around the oven, keeping the interior sealed off from the smoke.
 
Benjamin Dinkel
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It might work, but it also could be that the gap is not big enough. Also my inner oven box wasn’t all that sealed, lots of holes, that would then let flue gases in.
Also you would have no insulation then, probably loosing as much heat to the surrounding as you get into the oven.
 
William Bronson
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Maybe you could plug those holes with refractory cement?
I think RapidSet cement could survive those tempatures, and its cheaper than refractory.
Set the inner steel box with the opening facing upwards and cast a slab in the "bottom".
Create an inner form and use it to cast the roof,,base and sides.

The barrel ovens generally have  have an inner barrel, outer barrel, layer of insulation and metal skin.
You could immitate that by usung the insulation that you removed and some aluminum flashing.
Ive had good luck covering rockwool insulation with a cement coating over metal mesh.
 
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An EPA Certified and Building Code/UL Compliant Rocket Stove!!!!!
EPA Certified and UL Compliant Rocket Heater
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