The top knob is the diverter, which sends water to whichever function you choose! the hydro massage jets, the monsoon shower head, the handset, or (on whirlpool models) filling the bath. It only runs one function at a time.The middle knob controls water pressure. The lower knob is the thermostatic control, with a safety stop at 38°C! press it in if you need to go above that.





