I am curious if anyone has built their own wood fired boiler. I don't have any plans to do wood fired heating for my home but I would love to have on to heat my driveway if it could be done reasonably. I am thinking a poured concrete pad with pex tube laid in it to form zones. Obviously the goal would be be able to start a fire rather than do a bunch of shoveling!
I don't think that a chamber in chamber would be very feasible to fabricate cheaply, I am thinking about a separate fire chamber and water box. The water chamber would be a semi-sealed system with some kind of anti-freeze in it. A circulation pump would be connected to thermostat that would kick it on when the water in the tank hit a preset temp.
These are just very rough ideas so I would love to see what others have built or hear other ideas!!