I'm trying to get a handle on typical values. What water supply temperature is typical? Has anyone seen any wild variations from published supply charts or are they pretty accurate? I'm calculating that I will need about 32 BTU/hr/sqft at design temperature. I was originally thinking about using staple up under the first floor, but the Uponor Appendix E and Zurn design manual shows that would require a water supply temperature somewhere around 180F! Joist Trak shows low 140s. A sandwich type system appears to require temperatures in the upper 140s or low 150s. That's for about half the total square footage that will be wood with an R value of .7 or so. I'll need a lower temperature for the other 50%, which is tile. Has anyone used Joist Trak? It looks like a quality product.