This is going to presume some special knowledge of the Double Shoe Box Rocket stoves and their iterations, so I apologize in advance if I don't describe everything thoroughly enough, or if I have fallen behind keeping track of recent developments. Please note that references to heating water assume you know all about steam flashing and the potential hazards when using home brewed water heating. if you don't know all about it, learn all about it, watch a few scary videos, and still treat that type of experiment with great caution.
I had a more typical DSR first, trying to include oven and water heater in successive bells after the initial combustion chambers, using a ceramic glass stove top and a stray piece of porcelain metal countertop over the water heater chamber.
That first iteration was a mess, a couple failures where pex tubing was too close to the heat, leaks of exhaust hastily plugged with wet clay, and a very shaky bell around the water tank in general.
Still, it worked more often than not, heated water and gave me some general experience with this new type of horizontal "riser", and then last year I decided to do a better overall job, and changed the design a bit, deleted the oven, and reversed the position of combustion and water tank, with a nice solid brick enclosure on three sides, poured concrete wall in back, and one and a half glass stove tops over the whole mess. The ceiling of the secondary (top) combustion chamber was still the glass stove top, and increasingly I started to use a ceramic fiber blanket to direct more of the heat over to the water heater bell. I bought a different IR thermometer that went to 1300+ degrees , and frequently that top would glow that brilliant amber gold color and scare the crap out of me, but it continues to function well to this day. Oh, I frequently was reading "HI" on the new IR showing I was over 1300 degrees.
Now we get to the fun part. This year, just a couple weeks ago really, I noticed several bright days in the weather prediction, maximizing my passive solar heating,and figured in a rush i could do the new design, the DSR2.
I always liked the idea of incorporating an actual heat riser in back of the primary combustion chamber, and by lowering the build about 5 inches in side the existing enclosure of the DSR I was able to add an interior ceiling to the top shoe box. So the combustion process continues uninterrupted forward to the exhaust from the top shoe box into the space under the glass stove top. The way I see it, (encouraged of course by Peter and the Donkey forums, this gives a longer /hotter combustion chamber and eliminates the soot I saw building up on the glass top if I were to put a pot to heat up on the stove top.
That dramatic reduction in temperature from direct contact with a pot, was similar to the loss of heat by the top radiating into open space, so really to get the riser effect of secondary combustion at all, the whole unit would always need to be covered with a CF blanket.. This new internal ceiling is like always having insulation around the whole shebang greatly improving efficiency of the stove, even while cooking.
One of the things I've noticed, especially with the stove door full open (another nice feature of the DSR2, is that rockety noise that got mostly lost with constrictions on air flow, p channesl, etc. Yes, I know there were some intense venturi effects after the port on the DSR, but with open air flow the DSR2 just burns more like the original J tube.
A more complete history of my rocket evolution http://www.permaculturebob.org/category/rocket-stoves/