Benjamin Dinkel

Yesterday I received the 3 revision openings and the ash door a friend of mine made for this Rocket.
I'm excited to start building at the end of the month.

Anne Miller wrote:I have read, here on the forum about folks doing what you want to do with rocket stoves.  I did not know this is called a heat engine.

I would translate “heat engine” to the core of a rocket mass heater. That’s where the rocket part happens.
Then there’s the bench or bell that puts the mass in the rocket mass heater.
I think among the RMH-enthusiasts we use the word stove if we want to talk about something to cook on. Specifically to make a difference between a rocket stove (often just sole metal pipes) and a rocket mass heater.

You could also fit a small J-tube (120mm, maybe 150mm) with the barrel and the exhaust in the former door opening. And a little bench along the thick inner wall.
The small J-tube would be easy enough to build without much prior experience. One downside is very regular feeding while burning.

Hi and welcome to Permies!
Usually it’s best to build the whole rocket in the room you want to heat. But I can understand that you want the dirt in a separate building.
I think building a batch box rocket (anything that’s not a J tube) in that separate room could work.
The confusing names are all different types of cores for batch box rockets (BBR).
Best case most of the core and the bell or bench would be in the room you want to heat and only the opening with an insulated door would be in the separate room.
If you want large intervals of feeding you need to build a large batch box. I would go for 8” (200mm).
I’m skeptical about using the existing brick chimney. Could you run a metal pipe through it?
Can you provide us with a simple sketch of your house?

Since the site is all silt and no clay we needed to organize some clay for the cob bench.
And since I'll be building a guest house soon with light straw clay and clay plaster on the inside, I seized the opportunity and we ordered 6 tons of Alpañata.



That's the same material they use to restore the Alhambra here in Granada. Once on site I'll have to make some test pucks with the available sand.

Excess moisture can be addressed with a lot of very dry saw dust. I don’t have a urine diverter. They tend to block up and I find dealing with pure urine way worse than the mix of it all. I am quite happy with the simple bucket system. More water would just mean more saw dust needed and shorter intervals for each bucket. So in total a bit more work.

There are these plastic mesh things, that let the grass or whatever grow in between. Of course the question is how natural a plastic grid would be. But it would look natural, let water pass and give you traction on muddy days.

True, I hadn’t considered that.
The whole bench will be plastered over with lime plaster. And I’ll have plaster mesh with me. Maybe I’ll go for 3” of cob with more fiber on there and add a strip of the mesh to unify it all a bit.

Hey Glenn,
thanks for your input.
The costumers do want thermal mass. They have a (poorly drafting) diy mass stove now and definitely like heat storage.
Do you think cob is not structural under 3" or why do you mention the pavers?

I second that notion Glenn.
I was wondering if that gap between core and wall wasn't a bit tight.

Also, is that flexible corrugated stove pipe in the background of one of the fotos? I'm sure you would get much better draw from a straight, smooth metal pipe.