Lot's of good advice here about lot's of good boilers. I would like to reiterate one point that has already been made and that is regarding properly seasoned wood in a gasification boiler. I cannot over emphasize the importance of getting the wood you expect to burn seasoned to below 25% moisture content. Once you go much above that you can expect a substantial uptick in maintenance, more "fiddling around" to get it to burn right, if at all, more difficulty kindling a fire and reduced efficiency/output. If a person reads back through some of the threads where people have had issues with their gasser, you'll find that a good share are due to "wet wood". One other thing I have to say is in regards to a brand that I haven't seen mentioned yet in this discussion and that is Garn. They are more $$ but if it's within your financial capability you owe it to yourself to check one out. There are no adjustments, no variable speed blowers, no oxygen sensors, no dampers, not even so much as an aquastat. There is also no need for added complexity resulting from field engineering external storage. They are in a class by themselves when it comes to being simple. The design is 30 years old and it surpasses the EPA Phase II standard by a wide margin using the more accurate ASTM test method. There are many out there yet that are 25+ years old and still chugging along which is a track record few, if any can match. An astute observer of this forum will notice that many come here and talk about having to tweak and "fine tune" their boilers, as well as figuring out how to add storage, but users who end up with a Garn usually disappear once they get them installed. There is a reason for that.