George,
Radiant heat is the way to go. We are thinking about heating the second floor of our garage with the outside boiler and radiant heat would be my choice. I have a small gym on the second floor of the garage that doesn't get used much in the middle of the winter because of the cold. If I heat that area I will have no excuse for not working out in the winter!
Maine standards will allow used units to be grand fathered and reinstalled at another site within the state but as far as I know you are not allowed to bring used or non-compliant units into the state ME as of March......My guess is that these units are still making it into the state by private sales, but I doubt that reputable dealers are taking that chance .
Of the states that do allow outside wood boilers I believe Maine and Vermont are the only two states that are currently restricting what can be installed.
