Please have a look at our new wood planning guide. We have had a similar planning guide for pellet boilers for years and have now created one for wood boilers. It covers all of the most important aspects of wood boiler planning; including boiler and thermal storage tank sizing, clearances, chimney design, and plumbing layouts.
You can have a look at it here.
If it is a pellet boiler that you are interested in, the Pellet Boiler Planning Guide is located here.