Wow, I guess I just never knew that an underfed boiler was so versatile. I will have to look into them more I guess.
My father has one; a brand new boiler that he bought but has had nothing but problems with it. I am not sure what is broke on it now, but he is burning oil instead of pellets. This new boiler is broken down far more then it runs unfortunately. On the last point...that is the truth. I tried to talk him into burning coal and going with that sort of boiler, but he is stubborn sometimes, and when he gets something in his head, he cannot get it out. He works part-time at a hardware store and they sell pellets but not coal, and so was convinced that is the way to go thinking coal will always be hard to get, but me...I greatly dislike pellets.
Now wood chips, biomass, whatever you wish to call it; I am really interested in that. As I type this I can hear a wood chipper on my neighbors land churning trees into chips. Any logger of any size has one around here and I have the capacity to make them myself if needed. Someone told me it requires a lot of air coming up through the grates from beneath and that a chain stoker is required to get them to burn. I figured that would be a lot like bituminous coal with some preheated secondary air. Our local school has one, having switched over from oil a few years ago. It is a huge school, holding about 1200 kids from K-12 and uses about one load of chips per week in the winter, BUT it requires clean chips.
Still it has enough capacity so that their sidewalks are all radiantly heated and even added a few more this year because the boiler has excess heating capacity. One of the maintenance guys is a good friend of ours and goes to our church so I will have to ask him about the design of it. Maybe it can be scaled down.
Thanks for your input. I know you have built quite a few boilers and stoves and so I know you realize that it can be done. After watching my father pay 5K for his junk boiler, I figure I can do the same thing for a whole lot less. heck I might even be able to make something that works for a whole lot less!