If you have very high ceilings or a lot of windows then you might want a suplimental heat source.

Why are you getting a boiler? I have a system from Radient tec in Vermont and it uses a regular hot water heater. I'm really happy with it, except under wood floors. If it's a proplem bring it in from the US, I think you could get similar conponents there. I liked dealing with them because they had very good customer service. I learned a few tricks that made installing it easier. If you decide to go with that kind of system, you could look up my old posts.