Small barrel RMH

Can a RMH be built with a small 10 gallon [17 inch H, 14 inch D] steel barrel?

How big [small] would the J-tube have to be?

The taller your system the better the draw. I have not heard of rocket mass heaters combustion tubes shorter than 25" So by the time you put your 17" barrel over that, you are about 10" short for your barrel.

I have seen rocket stove heaters, that short (no thermal mass exhaust). I don't think you would get enough draw to run the exhaust through a thermal mass. If you do a youtube search for rocket stoves, you can find some that are made for heating a small space quickly that are that compact, and use a 4" J-tube.

Good luck.

Would I be correct to assume two things:

1] Even with a lower draw, the gases in the riser would still mix and burn the residual gas from the combustion.

2] The temperature, BTU, output would be reduced.

The first point is the primary concern, but the second point might mean that the temps in the riser would not reach the levels needed for complete combustion.

I was thinking of a small area use for such a stove. If it could work, the thermal mass would envelope the barrel and there would be virtually no horizontal run for the exhaust.