I didn't see this thread until now. I happen to have a wood burner for "auxiliary" heat in my home. It is an outdoor version.
The burning unit itself is a large double walled boiler. Fire is in the inner chamber and that heats water (400 to 500 gallons) in the supply between the two walls. The water in the outside boiler is at atmospheric pressure, and the burner operates at somewhat reduced oxygen.
A circulating pump brings the water to the house. There is a neat little heat exchanger in the house that heats the water used for domestic heat. If the wood burner is off, domestic heat is provided by a propane boiler. It is probably a bad idea to use a single water supply. I have not seen that done.
Efficiency is of little concern as the fuel is waste wood and would probably be burned in a pit outside just to get rid of it. No non-commercial individual I know actually buys the wood used. He have a real surplus of dead ash at present.
The circulator motors are quite small, usually 1/25 hp to 1/4 depending on the BTU. My propane house furnace is 100,005 BTU and uses a 1/25 hp circulator. The circulator to the wood burner is 1/4 hp, but the pipe is larger (1-1/4") and the distance and water volume greater.
A medium size home will go though several cords of wood in a Winter, so wood from a single tree would hardly make a dent. Maintenance is minimal, except the larger circulator pumps are expensive when they need to be replaced.
As mentioned, they are quite popular in rural areas that otherwise depend on propane for heat. One downside it that the propane dealers are allowed to charge more, if you have a wood burner. That additional charge is in the form of disallowing certain discounts. Nevertheless, a home that might take $2000 to $3000 to heat all season, will get by with less than $500 in propane. A neighbor says his propane bill is only $100.
The other downside is the need to add wood on some miserable days.