8" rocket mass heater on my wood floor and juicebox chimney

I'm designing and building an 8" rocket mass heater on my wood floor using methods from the Bonny8 design. Would a 6" vertical chimney using the 'drinking straw' method function to take the exhaust gasses up through the middle of my house? I intend to have the vertical exhaust near the barrel to warm the chimney and encourage the exhaust to go up the chimney.
I'm also wondering if anymore experiments have been done on the cob hat with faces radiating downwards. (It was "thinking out loud" in a blog where Paul and Mud were talking about it)

With a chimney going up through the middle of your house, my opinion is that yes, that will most likely work fine. If you have odd wind patterns or tall surroundings, there might be issues.

Regarding the expanding cob hat with surfaces facing down, my experience is that areas of cob that are significantly farther from the heat source will hardly ever feel warmer than the general room. My bell has around 6" of cob over a brick inner skin, and at the corners (even though they are rounded to 6" radius) the surface does not begin to get warm until 6-8 hours of continuous burning.

The one way an overhanging hat could be beneficial is that rising heat from the sides of the barrel would hit the hat surfaces and warm them, reducing the amount of instant convective heating in the space and converting it to stored heat.

Hi Ron,

Welcome to Permies.