How small do you have to split wood for an RMH

How small do you have to split the wood for a RMH?

After it is started, can you use larger pieces of wood?

Would you have to design a larger stove to use larger pieces of wood?

By large, I mean about a 12" diameter log split down to quarters, or maybe a bit smaller than that

Most of the designs I've seen have a very narrow feed tube.

The typical solution is to use small wood, rather than splitting logs down to the size needed. Tree trimmings, and wood produced by coppicing fairly frequently, are two common sources, but some people have arrangements with carpenters or similar.

It's possible that whatever source of cordwood you're drawing from, also produces smaller slash which is unsuitable for either kindling or traditional firewood, and would otherwise go to waste.

8" system has a feed tube of 7"X 7 and 3/4" after a good bed of coals is established you can burn a single chunk of wood the is slightly smaller than the feed tube and it will burn on its own coals. it is best however to burn two or more pieces of wood so they feed each other heat.  the intent of the stove is to conserve fuel so its as Joel said built to burn small branches and pairings off trees. the other consideration is that the stove uses a fraction of your normal winters worth of fuel so its no big deal to split the wood as it comes in. the side note and question is how much you have to tend the stove. this depends on how you have the wood split but for us we tend it about once an hour and that is usually to just make sure thew wood is feeding correctly a hard wood like maple will burn set of three 12" long sticks for about two hours. depending on your wood type this could be a shorter or longer time period. i would say about an hour and a half per load is average.

do you need to get up during the night to feed it or is the mass hot enough to let it go out and just use the heat radiating off?

thanks
gary

that depends on how much mass you put on the system. Usually our stoves have about 20 hours of mass. what that means in my world; is I can feel heat coming off the mass 20 hours after i stop heating the mass.

so the short answer is no you dont have to feed the stove all night once its up to temp (warm to the touch or about 120 degrees F under cushions).

It would be a good idea to read the rocket stove butt warmer thread and many of the others. most of your questions will be answered, it would also be good to read the book (Note: this is not selling the book. you can check it out from the library) We tried to put as much information as we could in it for the builder.