[strategery]

Very tight building with great insulation in zone 5. If one wanted to use a hydronic heating system, say a boiler and 3 or 4 radiators, how would you go about finding a heating system for such a small load? Would you want to run the radiators off of a water heater such as a vertex or a tankless?

Or are radiators and hydronic heat less sensitive to oversizing than forced air? Smallest boiler and furnace I could find was about 50 btu's.

Square footage is about 1000. New windows, new doors, wall & attic insulated to the max.

 

[beenthere]

A standard 80% efficient boiler will generally have enough water content that along with cast iron rads, a slight over size won't be a problem and cause too much short cycling as long as its a cold start boiler.