Hallvard Benum

Thank you so much for the quick respons Bob.

I now see that the best way of doing this will be to make a regular RMH and extract the heat from the barrel somewhere. Sounds like the setup you have is a good one.
Have you insulated the copperspiral on the outside of the upper halft of your barrel?
I plan to set up this rocketstove just outside my basement where my technical room is, so that I can run the hot water in there if it works out good.
My woodburning stove has several security measures installed. Cooling spiral connected to the mains with a overheating thermostat in the stove that open should the stove reach any critical temperatures.
Also I have pressure valves connected to a expansiontank. And then I have an unbreakable power supply that can run the pumps for a couple of hours should the electricity fail.
So I'm not worried about putting heat from the RMH into the system. Everything is also connected to a 1000 L accumulatortank which won't boil in minutes. I have actually never had the tank above 70 degrees celcius.

As you were saying about size I would like to go as big as possible. I saw another thread here that talked about loading long poles of wood and thought I might try that. Not with an open slide as suggested there but rather with rollers to be sure nothing jams.
How big can one make a firebox, and what kind of firewood can you use in it? Can one use regular split wood as one uses for a woodburing stove?

Thank you again so much for the reply and I will update you on my progress when I get started.
Any advice is again greatly appreciated.

Hi all.
I want to start with saying thank you to everyone posting all these very interesting ideas and suggestions in this marvelous forum!
I am also planning to build a water heater rocket stove and just found this very interesting thread.
I already have a water based heating system in my house based on regular firewood and solar water panels.

Since I'm a rookie that haven't even built a rocket stove yet please do try to tolerate some maybe not so enlightened questions.
For the purpose of just heating water, as mentioned in this thread, is it necessary to include the barrel over the heatriser?
Could one not just add a meter or so of chimney with a coppertube wrapped around and insulated above the heatriser to extract the heat?
Or would this somehow kill the draft/suction, up/down flow of exhaust gases that is created with the barrel.
And how long does the heatriser have to be to ensure good efficiency?
And what sort of temperaturs can you expect in the exhaust exiting the heatriser?

My plan is to use a fairly strong water pump to push the water through the copper spiral (about 1" thick tube) and circulate it in an open system so that pressure buildup should not be a great danger. I will then circulate this water through another spiral in my accumulator watertank (1000 liters) that heats my house. Or I will circulate my small outside tub through this setup depending on the occasion.

Any suggestions and explanations will be greatly appreciated.