Deagon Demientieff : Short version, your last choice is out, here's why ! With a 6''
Rocket Mass Heater RMH,you get to have 30' of Horizontal pipe to embed in a thermal
mass. That is 30' - 5' for every Elbow in Your system ! A three elbow system is about the best you could hope for, that is a straight run off of the manifold below the barrel,
8' and then use (2) 90 degree elbows to turn around and come back to the barrel and then a 3rd 90 degree elbow for your final vertical chimney straight up through your
roof !
While the RMH is a wonderful heater it works best if you start out with a Blank sheet of paper, put the RMH in the center and then design a house around it !Often starting
out with a house and trying to retro-fit an RMH inside it Sucks!
With this 6'' system you Have to have a rectangular or oval shaped house ! And its not me you need to get to change my mind its Physics and Mother Nature ! You are not
the only one even to be caught in this trap, With a bigger system we could have a few more elbows, but a bigger system would be to big for your space ! Draw up a sketch
of your present structure, and shoot it to us, and we will play with the impossible.
I want too suggest that you go to
Rocketstoves.com, to download a PDF Copy of The Brand New 3rd Edition of
Rocket Mass Heaters, this will help you to figure
out what is possible on your own, if we come up with some thing it will be a need copy of the 3 elbow set up, so if you want to wait on an
answer from your fellow members
here at Permies, before you invest in the book I/we will understand, but you will need it often to understand exactly what we are saying to you if we can save this Build !
You can be sure if together we say we can do it, it can be done, we will not allow the creation of a failed RMH and a Homeless House
Dragon !
For the good of the Craft ! Big AL