Detecting if my attic fans are on or off

[Hal3]

Try something like this:

Devices for sensing water softener cycling?

Thank you all for the suggestions. I combined them into a solution that I think will work. Rube Goldberg would be proud. I created a string with a "tail" assembly to go down the backflush drain. The string is attached to the "bacon" motion sensor which is suspended by a rubber band. I am expecting that the backflush stream will tug on the string tail attached to the motion sensor stretching the rubber band and triggering the motion sensor. Now, we wait. [PSX_2021052…