Thanks for the replies all.
My idea is to make a masonry structure that is more of a table than anything else. so about waist height to match the other racks in the greenhouse, and build internal horizontal passages for hot gasses to trap heat before being exhausted.
Most rocket mass heaters go the direction of the barrel riser for instant heat and then a low bench. But I don't like the idea of having the traditional barrel riser that goes with RMHs, this is mostly based on my biolite campstoves which inevitably start to rust to pieces with continued use, so there's a better chance for gas leakage and such.
A J-tube design was my initial thought, but that design seems like it would require a lot of babysitting to keep the fuel topped up, and it wouldn't be compatible with some of the fuel I want to burn (magnolia leaves). I've thought of using a J-tube for startup to get the draft running, but the main combustion chamber would be either a russian stove style with a grate and blower chamber below it, or a batch box rocket stove, or some combination thereof. This is the unknown territory I want to experiment with.
I've been consuming a lot of content on the russian style heaters, including kuznetzov's plans and builds by expert russian stove makers. I speak just enough russian to get an idea of what they're saying, but I miss at least 50% of what is said. Since posting this I've found that there is a large movement making small versions of these structures in south america, and spanish is a first language for me.
My issue with most of Kusnetzov's designs, and the chinese style passive walls is that I've never laid a brick in my life and I live in the seattle area where we can get BIG earthquakes, so I'd rather not have the stucture collapse and take the greenhouse with it if it did. The greenhouse is not a custom design.
