Quote Originally Posted by Voicecoil View Post
I'm thinking of adding a slight enhancement to the "pump switched by VFD" thing by sticking a flow sensor in the return line to the reservoir driving a relay. It's then pretty easy to sound an alarm if the pump is energised but insufficient water's flowing.
If going to that trouble I'd be more inclined to fit the temp sensor on the spindle than worry about water flow. Or have both work together.