what are the limits of a rocket mass heater ?

i am thinking of heating my greenhouse(30x96) with RMH .have never built one or used one. checked out all the info. and vids on the net but didn't see any thing on what max. length of exhaust tube can be.sincethe exhaust can be ran horizontally is the exhaust considered to have draw or isit forced out by the burn chamber?also does anyone know kind of BTU say an eight unit would put out? how big of a unit can you build?

I have been wondering how they handle more intense fuel. Like what would happen if they burned stuff similar to pellets in some way? You know... could you put in some really hot fuel? Would it allow to heat a bigger place? Can you make them bigger to heat bigger places? (maybe centralize them to have a very large re-burn chamber?)

Bueller?

Well a 12 inch system will go about 100 feet a ten inch about 75 feet and 8 inch about 50 and a six inch about 45. max. BTU well if you folks want to send me donations i am still trying to raise 5000 to get an 8 inch tested by the folks who do wood stove testing.
as yet i couldn't give you BTU. I can tell you that mine burn around 600 degrees on the surface of the barrel and exhaust at about 100 deg. we are in Tonasket washington where its cold and snowy. our stove is our only heat source and we burn about 2 cubic feet of wood a day (Well evening) our house is warm for about 20 hours till we need to fire our stove again. Several stoves have been built in green houses and i recommend the 8 inch system for most of them. a 10 or 12 inch system is a bit of over kill unless you want your plants cooked when you harvest.

a little draw and alot of push the barrel radiating and hot stack effect push exhaust through the system. but you can give the system a bit of a boost if you configure your exhaust to give you draw.

Paul talks with Ernie and Erica about rocket mass heaters in this podcast: rocket mass heater podcast

They talk about how big you can reasonably go with rmh's