Jim Sanders : 1 and 1/2 inch is the minimum for a 6'' system, and 2'' is the minimum for an 8'' system, I freely admit that this is a problem !
Assuming that you are building on a
concrete surface and not on
wood, you still want a layer of insulation under the bricks that make up the
bottom of the Burn Tunnel/Combustion Chamber, Have you done the math to prove to yourself that you can have a full sized
Feed Tube, and
Burn Tunnel and have a Heat Riser that is 3 Xs as tall in total as the feed tube is deep? You must also add in the proper gap to the barrel!
Even if you eliminate an
ash pit at the bottom of the Feed Tube, and you should you are making it necessary to feed your R.M.H. with very
short wood more often !
To
answer your last question, yes you can cut a hole in the side of the barrel here is a good place to 'go big or go home " 2-3 Xs the regular
Cross Sectional Area ! The inside walls of this area need careful attention, I would build a form out of hardware cloth and use a little fine
chopped
straw, for your first coat, finished off with a fine sand Clay coat as smooth as sheet rock, this is the hardest pert of the build to get right! BIG AL
