I’d say the average burn tube temp is about 750 to 950.
you are not breaking any rules. do as thou wilt... are you saying that because you are using metal? at those temps there is no way you can call it a rocket stove so no "rules" have been broken and you will be able to use that system until the cows come home because there is no way you will be able to break your metal down let alone all the energy out of your wood.
Breaking "all the rules
OK... finished reading your thread and if I understand correctly, Your "J-Tube" is actually an "L" with an extended horizontal feed tube ("Magazine"), where you can place a longer log?
Not sure, but is the diameter of your feed tube wider than your 6" system? (I've read in the book and elsewhere that the entire system should use the same diameter CSA.) Have you experienced any issues/problems with this configuration?
For safety concerns, I'd like to stay with a vertical feed tube, not wanting to risk sparks or burning debris spitting out. Even in mine, I did have one instance where a hot ember was thrown up and out of the feed tube (guessing there was wet wood in there). Since then, I've created a fine wire mesh cap to use when I want to burn without my adjustable damper cap (They're interchangeable.)
Richard Jarel wrote:what I meant with my last question was: any ideas as to what temperatures I could expect at the exit duct fitting at the bottom of the first bell?
additionally, I'm :guessing" that if I use cob (collecting heat and insulating that ducting) around the ducting exiting the first bell I would retain higher temperatures for the 2nd bell?
My biggest question is: Can an "S" shaped burn tunnel work?
(Example: If i cover the first bell with a "lot" of cob, etc... I think it will not only absorb the heat for later distribution, but "should" keep internal temps higher (?)... If I then cover the ducting going to the second bell with more cob (insulation), the heat drop from the bell # 1, should continue at a higher temp than if I left that ducting bare metal radiating....)