Dave Agar

If Im reading correctly your pipes are nearly the same diameter. in a short distance a minor diameter change poses negligible effects ,  consider the laminar flow when you build. keep things flowing.

Hi, I have recently got my 6" batch style operational......When I built it I  had on hand an old 50 gallon  metal barrel from the 1920's, it is exceptionally heavy, 84 lbs to be exact.  twice as heavy as today's barrels and twice as thick. The only thing I have noticed its a few minutes slower in radiating heat.   my old wood stove which I replaced had 14 gauge metal as have today's barrels, they are lighter and faster to radiate to heat......as for draw I assume it has minimal effect as is absorbs  heat, the air volume diminishes and is routed downward through your mass in the same fashion a thinner bell would do. A tall stack adds to the exhaust draw also.
how high is your stack above the riser floor ?


Dave

Guys, I'm at the point of build on my 6" RMH where i'm building the P tube but find myself stymied on how to mount it in the fire box .....Any sugestions ?

Thanks Guys,  I'm getting a better understanding of the density and size limitations.
I'm heating 1008ft2,  ten ft  ceiling half the insulation values as posted above.
Dave

I'm planning on building  an 8" BRMH this coming season in my shop. I have a daily burn time available of 4-6 hours. (Plenty of BTU's)   I will be following Peter van bergs batch system and applying the CSA dimensions and secondary air tubing. using a single 55gal bell for my sensible heat.  
My primary concern is to keep the mass warm for a long period.  
If 7500# mass  is good then why wouldn't  say 9-10,000# offer a longer radiant heat time?
I have read cover to cover the latest book by that couple ( sorry the book isn't in front of me to thank the writers. BTW its a great book chock full of info.)
I did not see anything in it about over building the mass,  pro or con. can anyone share their thoughts on this?  
Drafting or venting will not be a problem as I have designed in a non intrusive mechanical system located at the building outlet  for if or when its needed.

Dave