Allow me digress about this, "thermo" means heat and "stat" means stable (KISS phylosophy)... ThermoStat = Stabilized Temperature Though i can think of a thermostatic system with no sensor at all, as a matter of fact! Anyway we seem to refer to some common language (for example, thermal mass behaving as a low-pass filter within a closed loop system), whatever. So, briefly put i didn't think it was fair to compare the DaVinci to a "Rheostat" (and i still don't!!) - which by the way says absolutely nothing about what side i'm on. You've confirmed what a photograph already proved: there's a sensor and it's there to implement thermostatic control, that's it. A cat IS a cat. Your input was appreciated, in any case! So, thanks again. Good day, have fun!!