Paul’s 8” system in the Fischer Price house IS very nice! I spent two weeks at Wheaton Labs in 2019… both 6” and 8” work well. J-tubes are more efficient and (I think) easier to light than batch boxes. Below 4-5” systems are MUCH finickier… too much laminar flow/resistance along the edges of the path of gas flow. 10” or larger gets TOO hot…

cool! 😮 I wish to visit Wheaton labs someday, it is a bit harder coming from the EU. Else I would hve been an ant for many years... Yeah, I was initially thinking about a 4" system but I dont need that extea finiky whatsha-ma-call-it. 8" is proven and just works, so I will go with that. My next steo in this is to build an outside J-tube #RMH but need to get the riser materials first... So many wonderfull projects, quite addictive, and each steps makes me pollute less and increases my happyness. #permies #rocketmassheater #homestead