Needs at least 8 inch exhaust or bigger ,go 10 inch if you use the mass or size down the inside to same or smaller tunnel, space at to of barrel needs to be a hair more area than the tunnel, square inch figure it .
exhaust must be at least as big as tunnel that simple, don't know why these folks that know won't tell ya and than they want to sell a video that may not either.
If you want confirmation in your area go to an old havc heating and air man they know lots more about the tech on this than any rocket stove forum yet has to offer.
than you know it will work before you start.
This is where bigger is better on the exhaust if you running a long run bigger is a must.
Really makes me mad sometimes when people want money for info that was free to them in the first place , and trying to keep this maybe [b]2 thousand year old tech a secret.[/b]
