I read somewhere that you can't use a tankless water heater for hydronic floor heating. Yet the tankless heater I purchased (Nortis or something like that), specifically states that as one of the applications. Is there anything I need to be concerned about?

It may shorten the life of the heater. Regular heating boiler is make of steel or cast iron... if they said it work.. it will work... I'm also interest in put one to supplement my electric heat (( to save at least $500 yr)...