Hello and good day to you all.
Having recently completed a rocket mass heater to to specifications of "the Bonny" plans by Ernie,i realise that a bigger (larger diameter) fire feeder tube is needed for the purposes i require. Although the b"bonny" uses a 8 inch tube system,i have had to use 140mm tubing (+/-) 6 inches diameter some the fire feed tube is the same. My question is ,what is the maximum diameter to which i can increase the diameter of the fire feed vertical tube? If anyone has done this type of adaptation ,or knows the dynamics of this ,i would sure appreciate your input before i go cutting my stove about..