Ernie Wisner wrote:no problem thats why Erica and I hang around here.
have fun experimenting.
and yes you will want the same cross sectional area throughout the stove. (8 inch all the way)
Glenn Herbert wrote:The system diameter does not directly relate to the riser height. It is common to make the feed tube height 1 1/2 to 2 times the system size, so 12" to 16" for an 8" system. Using the 1:2:3 or 1:2:4 ratios, this would give 12:24:36, 12:24:48, 16:32:48, or 16:32:64 feed tube to burn tunnel to riser. (Measured along the outside edges of the components.) The burn tunnel can and should be shorter than 32" in most cases. 1:1.5:3 is another ratio I have seen, which would give 16:24:48, quite practical with standard materials. I would not cut the barrel down in any case; the taller the riser is, the better, within reason. Extend the riser to make it 2" below the barrel top.
An 8" J-tube system can ordinarily support up to 50' of horizontal ducting, minus 5' for each 90 degree elbow.
Thomas Tipton wrote:Has anyone ever built a rocket stove with multiple risers? And if so, what were the results?
If it failed, can you describe the failure mode.
Thank you for taking the time to read through my crazy.
Thomas Tipton wrote:... so while I have your attention perhaps you might indulge me on why you attempted the twin riser design. Were you attempting to lower the riser height requirements as I am doing, or was it for another reason? Just curiosity perhaps?
Thomas Tipton wrote:Thank you again. It's a great honor to hear from you.
I would suggest that you may want to make the tall bell only as large as it needs to be for proper function, and add a bench-style bell to absorb the rest of the heat before sending the exhaust to the chimney.
Long runs of parallel ductwork would have less of this issue, as friction would increase dramatically with increased flow, tending to equalize the competing paths.
Erica Wisner wrote: I have never seen one that was an improvement on the brick J-tube, for smokeless performance. [Edit: As of 2018, I have now seen 2 batch box models built and operated by Peter van den Burg, that did burn amazingly clean. However, I've also seen other people have major smoke issues using the identical batch box stoves without Peter's meticulous procedural care.]