I noticed on the Watts site that they state those valve kits are not supposed to be used with tankless. That was my reading of it anyway, though I guess if it works, it works. There's something I'd like to understand about these valves and recirc systems:
If they essentially use your cold supply line as the return recirculation line for the hot until it reaches 98* don't you now have essentially 98* water in your cold line? So don't I end up negating the "savings" by having to run the cold at the tap for ~10 seconds in order to get a nice brisk rinse after shaving?