I'm considering heating an additional of a house (approx 1000 sq ft) by using radiators (like buderus type) and a supply of hot water from a tankless water system (like rinnai, takagi). Have any of you done something like that? Does it work? What are the up/ down issues when considering a boiler versus a tankless water heater in a heating system? I'm not considering any other options/ advantages (like having hot water).