...or is it mostly comfort? I guess I could retrofit it in my 2 story house; I'd like to put in hardwood floors upstairs and I bet there's some product or system to do that, and the downstairs has basement access. I bet it would be really comfortable to walk around, and I realize lower circulating temperature water could be used. But, what is the economic impact? Can a setback thermostat be used, even if only for the upstairs, which isn't used too much during the day? My wife isn't working anymore, so it's not a question of turning it down while we're both at work. How much of a lead time to get things back up to temp? Just wondering if it would be for me. I know my wife would like the warm floors. Thanks.