RMH Help

Some how in our move I lost my copy of RMH book. I am wanting to build a earthsheltered green house this fall and want to build in either one or two RMH. I can not remember from my reading how long of a pipe run I can make with 8" flue in a cob bench. I remember that if it is too long there will be too great of a temp drop before exhausting. The other question is that for the size of the green house would I be better to have two RMH or engineer up to a larger diameter and length to heat more space? your thoughts or opinions would be helpful.
kent

Sorry no responders

I did see the book on PDF for $15 though :

http://www.rocketstoves.com/index.html

Thanks for the reply. In desparation I tore through some more boxes and stuff from our move and found my copy.
kent

Groovy

I have to order a book myself, I need a good simple design for a cold Maine basement

Your answer.. It depends.
Somewhere between 30 and 50 feet.
It ain't in the book, but you can go further if you step down in pipe size a little.
I have NO IDEA exactly where to place the steps, no one's nailed that ratio down yet..
I CAN say that I've seen it work and that a little experimentation will answer the question for your particular need..

Thanks for all the replies and PMs.
kent