My wife and I will soon be building a new home in the mountains of Utah. Ultimately we'll retire there and live full time but for now we'll be there part time only and the home will be empty for weeks at a time. I'm putting in tankless water heaters so I don't have to heat water when I'm not there. We would really like radient hot water floor heat but how does that work with the tankless water heaters and not being there all the time? Also, our builder tells me that we'll need a forced air system anyway since we'll need AC for some summer days. We don't want to pay for 2 heating systems. Any ideas? Are we stuck with forced air? The tankless water heaters is the #1 priority, or so we think now. Please help.