I've been using the Therma Dry machine since November last year, it's agreat system, I don't use anything else. Yes put simply it is a Victor rotary with a high powered heater (no not a hairdryer!), Dry Fusion is a Columbus Thermomachine (rotary with a heater!).
The reason why the heater is so important is quite simple, heat assists in nearly all cleaning systems, imagine HWE with cold water. The second reason for heat is that it dries the carpet quickly, Therma Dry or Dry Fusion without heat is bonnet buffing (almost). I think that the heat also may assist in curing the protector also. In short the heat used in these systems is vital to achieve the excellent results that I am currently achieving.
Regards
Nobby