I’ve had a Rachio Gen 2 installed for almost 4 years. A couple of weeks ago, it cycled my valves and pump on and off over 600 times over the course of an hour. I had to replace 3 valves ($150 total for the parts plus my time) that were damaged due to this. I suspect the life of the pump was shortened by this event as well. Rachio is aware of this and verified in their logs that it really did happen, but the firmware has not been fixed yet.
The problem was due to a bad rain sensor (not Rachio’s fault) that apparently would alternate between an open and closed circuit every 5 to 10 seconds. I woke up in the middle of the night to the sound of hammering as the sprinkler lines were constantly re-pressurized. The Rachio firmware does not have any sort of failsafe that would prevent a bad sensor from continuously cycling the system on and off every couple of seconds (Rachio’s fault).
I have implemented my own failsafe in the form of a middleman Arduino and a relay. The rain sensor is read by the Arduino and the relay opens and closes the Rachio rain sensor circuit. If the rain sensor triggers (opens the circuit), the Arduino will open the relay to stop the Rachio from running. It will then set a timer for 30 minutes and not reenable the Rachio before then, even if the rain sensor closes its circuit. Once the rain sensor closes and the Rachio is reenabled, the Arduino will not disable the Rachio for at least 5 minutes. It’s a simple solution that can prevent major problems. If you use a rain sensor (or any other sensor that could make the Rachio cycle your system), you might want to implement a failsafe of your own.
(not sure where this type of information would be posted in these forums, so I choose Troubleshooting)