yoshi Hashimoto

Thanks for this response.  I should clarify, this is not my actual first time ever rocket stove.  I did throw one together a few years ago, a simple J design using a paint can and tubing.  It worked well but due to it's simplicity I barely count it as a build. This is the first one I am putting any brain cells to work towards.

I just posted on here yesterday inquiring about the science behind maintaining a draft on a rocket stove.  Because I am wary about building something that may not work as I hoped, you will see that not only is my design ridiculously simple but is meant to have an initial phase (simple chimney straight out the roof indicated by the dashed line) and then I will transition to an experimental 2nd phase in which I add progressively longer horizontal runs.  I initially intend to encase a simple 6" wye stovepipe flue connection in concrete.  Once I find a configuration that I like, I will probably encase the whole thing in either concrete or gravel or sand.  Am I missing anything?

I should mention that this is for a greenhouse with very little monetary value, far away from the house, and only for use during the early spring when I'm trying to get seedlings growing. I don't need a lot of heat, it would just be burning for a couple hours each day max.  Also, it is not to scale.

https://www.flickr.com/photos/smallape/3479430795/
 image of bench build
I'm not referring to the simple J style stove, I mean the kind that features long labyrinthine exhaust path to leech maximum heat from the combustion, as shown in this example.  Conventional woodstove installation places a high emphasis on ensuring a good clean path without too many bends, and even the chimney outside of the house has to be raised above the ridge of the roof, all in the name of safety (maintaining stack effect), otherwise the fire may not stay lit, and exhause can flow backwards.  How is it that rocket stoves that claim to have virtually cool output can keep flowing, why isn't it dangerous?