Benjamin Dinkel

Hey Thomas, your Dragon is gorgeous! And getting prettier by the day.
May I ask why you’re avoiding the joints? Will they look terrible if oiled?
What oil are you using?
And how many layers do you apply?

Hey Glenn. Nice idea this thread.
What’s stopping me at the moment to build one at my home is:
a) I don’t own the house just yet
b) the position of the existing exhaust is not ideal for integrating the RMH into the existing floor heat system. Also that’s probably quite complicated and maybe not even such a great idea

Not in my case, but would be if I still lived in Germany. RMHs are basically outlawed by now because all wood burning devices need to pass a specific test to prove they are burning clean (dust particles). And proving that of way too costly to do for a self built stove.

I have used black tea and white sugar mostly. Often I add rosemary or herbal teas to cut back on the black tea. Also for different flavoring.

Fruit juice is super good for the second fermentation. That is when you bottle a middle to well fermented kombucha and add some more sugar or honey or fruit juice and flavors. Then you let it ferment further with a closed lid to carbonate it. Be careful, thin glass can explode. I use 1L thick glass beer bottles with a flip top.

Cedric Noussan wrote:
4) I wasn't aware of this option. Does the rock wool come in a roll? Is it wrapped around the riser like superwool?

No, don’t use rockwool instead of Superwool. So don’t make a 5 minute riser, it probably won’t survive the temperature on its own.
If you use firebrick you can just put rockwool around the whole core and then cob over it.

You can see it in my build (of a rocket oven) here.

https://permies.com/t/280509/rocket-ovens/Cob-brick-oven-rocket-technology

It’s the green stuff. I used sheets. But roll works as well.

Hi Cedric,
I’m sure the fellow scientists will find answers to all of your questions.

As to your 1) I don’t really understand what you mean. You’re building a 20x20cm J-tube? (8 inch) And you want to know the bell surface equivalent?

I also don’t really understand the channel idea. What material will you make them out of?
You say you have expanded clay. Could you use 10cm of that against the wall to insulate the bell from the wall?

To your 3: I think that should work. It all depends on how you make sure that the hot gas can easily distribute to both sides from the manifold. The exhaust will be in the middle reaching down (juice straw style)?

4) I’m assuming you’ll use firebrick to build the whole J? I don’t think that the expanded clay is insulation enough for the riser and burn tunnel. Rockwool (mineral insulation) will work and is pretty cheap.

Hope this helps and that a lot of others will join the discussion.

Hey Matt.
How well insulated are the walls?
How about the roof?
What about the door, assuming there is one?

Usually you loose most heat through the roof, then walls, then windows and doors.

Could you get under the floor and insulate between the battens/beams? A couple of inches of insulation could do a lot.

I understand you don’t want to cut up your freshly built shed, so adding another layer to the existing floor sounds like a good idea to me.
Clay and perlite won’t help much as you say.

How about cork (or wood fiber, let’s say 1,5 “) and a thin layer of wood or laminate or whatever (.5” or less)?

Hey Rose, very cool build. Thank you for documenting it here.

Fox, while I agree with you on trying to protect the board to avoid dust, looking at the fotos of the manifold I don’t think there’s enough space to make the riser thicker. So going with the wire might be the only option. The manifold area and area around the riser seems small to me in general (depending on the size of the barrel though).

Hi Rico,
all of those should be internal measurements, yes.
All cob isn’t going to last forever, but depending on the clay you can make it work for a while.
You will definitely need real insulation on the riser. Maybe cob first and then a more insulative material.  
All cob is going to loose too much heat.

Hi Alana,
a well built straw bale construction (off the ground, overhang of the roof and adequate plastering) should have no moisture problems. Straw bale construction might actually have an upper hand there, when it comes to difficult conditions for other construction to dry in.

Are there traditional ways to build in the area? Those usually take climate and available material into account.

Hey Joshua, I would dispose of the burnt paper along with any of the ash and coal produced in the process. I’m quite sure neither is safe to use for anything else.
Same goes for the dust created when sanding the residue off.
I was actually thinking of trying to find someone with an industrial sander. That would take care of all the dust and all the particles that I don’t want in my lungs and in my garden.