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Posts: 51
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A lot of the threads contain extremely similar nomenclature.

Well, I've been looking into these things for a while, but this is my first post around here.

I know I'm supposed to tinker and tinker, but I might as well tinker somewhere someone has gone before.

Values that I have in design:

Locally obtained material (essentially all adobe/cob mortar/cob mass)
i'm a little afraid of the barrels if children come big enough to crawl but not smart enough to understand its dangers
Repairable/cleanable without smashing it down every year.


The design in my head is like this:

Create an arched structure using adobe brick ala:



then making a J tube using more brick going underneath this structure. Then bricking up the arch to enclose the J tube. Obviously the arch has some kind of exhaust (more and more brick).

After the brick is layed to exhaust out, i would cover it all in cob, putting clean outs that are made of brick where needed and can be removed.

Questions:

1.) Would having such a thick mass above the riser be okay?
is the typical barrel purposely thin to keep temperatures up?

2.) When I'm thinking about dimensions and exhaust, should the riser volume be the same as the volume surrounding it under the arched area and the same as the exhaust? I'm guessing the feed would need to be larger because there'd be wood stuck in there filling the space.

3.) Is a round design with stove pipe more efficient in terms of flow or temperature?

4.) Am I asking too many questions?

I am aware of the workload.

I'm not as professional as this guy at arches, but i think i could do the masonry

https://www.youtube.com/watch?v=PB8TWMKHHMQ
 
Posts: 217
Location: US, East Tennessee, north of Knoxville
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One advantage of the barrel (and they're lots!) is quick woodstove style heat output.

However, leave the barrel off entirely and you have more of a traditional masonry heater. Rocket Masonry Heaters can be built with your choice of either a J-tube or a batch-box style "firebox".

And what you've described for your desired thermal mass, going with an all masonry bell type heater seems to fit your design goals. The possibilities are endless. Here's just one example of using a rocket J-tube "burner" in an all masonry bell heater:

http://www.dragonheaters.com/castle-build-masonry-heaters

But the bells can be constructed entirely of refractory materials (firebrick, clay brick) other than flue liners, and then faced with stone, brick, tile, and etc. Again, lots of choices.
 
Johnmark Hatfield
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Ah, that makes sense about the barrel giving off heat quickly before the whole mass is to temperature. I think I'll just have to be patient in getting the heat.

Another question: the typical beginner uses a 6" system. this is diameter right? So the root of 9pi is a suitable beginner square dimension?
 
Byron Campbell
Posts: 217
Location: US, East Tennessee, north of Knoxville
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H'm, 6" system? I've read that the experienced J-tube cob rocket builders often suggest that a beginner's first build should not be smaller than a 6" system. I.e. lots of first time builders want to go small, like a 4" system which tends to be problematic in getting it right.

You're actual system needs to be sized to your specific heating needs, taking into account square foot area to be heated, building insulation values, local climate, and etc.

Here's a link to the MHA's site showing an all brick masonry rocket stove suitable for a small cabin:

http://www.mha-net.org/docs/v8n2/wildac12g.htm


And a larger all masonry double-bell stove with black oven:

http://www.mha-net.org/docs/v8n2/wildac13e.html
 
Johnmark Hatfield
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either way. 6" is an ambiguous term that i believe refers to diameter of the channel which relates to draft. correct ratio of feed/burn/riser/mass and the materials used would be what changes with room size. does room size effect channel size?
 
gardener
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Location: Upstate NY, zone 5
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The usual implication of a reference to a 6" or 8" system is diameter equivalent. Usually exhaust/chimney ducting is round, but the combustion zone, or at least the feed tube and burn tunnel of a J-tube, is generally recommended to be square in cross section with square elbows for inducing turbulence in the combusting gases.

An 8" system is the basic whole-home heating size for colder climates; the correct size for your situation depends on a lot of variables. Telling us about your climate and house will help us advise you on that.

There is no real benefit to starting with a smaller build than you are going to ultimately want; using fireclay mortar, the bricks can be cleaned off and reused if you change your design, and of course cob is infinitely reuseable.
 
it's a teeny, tiny, wafer thin ad:
What makes you excited about rocket ovens?
https://permies.com/t/90100/excited-rocket-ovens
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