One thing the RMH cannot do is change the laws of physics. I understand it can be very efficient,im not questioning that. But if you need half a million BTUs to heat a large house on a cold day ,thats what you need. The wood or twigs or whatever burned will have to have to contain those btus to startout or its not happening. Also a 3 bedroom house could be 500Sf well insulated tight home or it could be 3000sf poorly insulated drafty one,makes world of difference.