Help With my rocket mass heater

Hi I am wondering about my rocket mass heater exhaust system. I previously had it buried in the ground of my greenhouse.
The exhaust pipe I used was 7" all that was available at the time. I was wondering if it was adequate to use. I did not cover the
pipe with cob I just covered it with perlite and placed perlite under then proceed to cover it with dirt. The pipe was buried
12-15 inches. So I plan to dig it up and build the exhaust above ground and insulate it with the perlite and make a cob bench over
the exhaust. I was also wondering if I should add any 90 degree turns to help with draft and extracting more heat from the gas
exhaust. I was also planning on trying to incorporate some barrels of water around the stove and covering them with cob too to
help aid in storing heat. I did experiment with running the pipe off the barrel and then in 2 directionsthen out the greenhouse.
Is this possible, I had a hard time getting draft to go both ways in the exhaust pipe any suggestions if this theory is possible?
Thanks for any insight.

JM41 McCoy :the rest of the year we are asking people to add thyeir General location and local climate # if they Know it ! look at your name, and then L@@K at mine.
Please go to thePermies Toolbox at the top of the page and clickon> the 'my profile'button where you an dd this information,we find it very helpful in answering your
questions !

Balancing the draft perfectly in a two pipe system requires a lot of luck or there are 'trip wires' that by vibrating, produce enough millivolts of electricity
to self monitor and report air flow past a known point and can be guesstimated ! This aint cheep and of course any change in layout or the grade that they run on
can affect the way heat is absorbed off of the two pipes, so you can have One pipe that is cooler than the other trying to flow denser air !

I am intrigued by your experiment with burying you pipe with perlite, Dry perlite kept dry would be insulating, however as the perlite can and will suck up a lot of water
out of the ground and water is such a good storage media for heat energy, if your native soil is only dampish i expect the % of water stored to be quite high, this is
physics and a little out of my depth !

When you speak of your raised beds you are speaking about insulating the pipe also, is this your attempt to get a more uniform amount of heat through-out your whole
system ? This would also shift the Balance in your two pipes.

Adding ! or more elbows into the system would slow the flow of your Hot Exhaust Gases which would increase the amount of time your gas would be in contact with the
piping in your horizontal chimney, You certainly can try it ! I 'wood' get Two identical thermometers to measure the discharge gas temperature at your ? 2 ? vertical
chimneys, a true balance is not as important as low temps

I expect if the system you built was perfect you would not be changing it now and I would even push for nice high work benches made of cob, your back will thank you!
however two 7'' pipes should be able to handle the Hot exhaust gases of an 8'' system easily so if you are rebuilding any way -go big ! For the good of the Craft BIG AL !