This winter I winterized my installed sprinkler system by purging all lines with compressed air, removed all mower from the timer/controller, and I thought I turned off the water supply to the system. When I was on vacation, I received a call from my neighbor that although it was 15 degrees F outside, my sprinkler system had activated and was watering the lawn... I had him shut off water to the entire house to stop the problem until I returned home. I found out that I did not turn off the sprinkler system water supply as I had thought I had done BUT the question is,..... how did the valve activate and turn on the water with no power to the solenoid?? I contacted the mfg but they wanted $10 for a tech assist.. no way.. just looking for ideas before springtime.