Moved into a new house w/ existing system. Came home to find one of my zones sprinkling away, even though the system is turned off (on my Irritrol Rain Dial controller). Valve to zone was open, so I shut the valve. Problem solved temporarily... Now I'm concerned about the system freezing, since there's obviously water in the pipes. Temperature was in single digits for past 2 days, but should be above freezing for a day or 2. What do I do now to keep the system from freezing up when the temperatu...
