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Irrigation/Sprinkler zone running with all the others


Hi Jim,
We recently purchased a home with an irrigation system already in place. The timer is an older Nelson controller, doesn't seem to have a master valve but does have a wire labeled P at the timer. There are 4 valves in the back yard and two in the front also a back flow system in the front. We replaced all the valves in the back yard as they were leaking and wanted to be sure they would work properly. Everything works as it should when manually turned on at the valve but when ran from the timer one of the zones runs when each of the others is scheduled to turn on. For instance zone 2 functions as it should when individually started at the timer but when you run zone 3,4,5 etc zone 2 starts first then the selected zone comes on (zone 2 loses some pressure but still stays on). I've tried everything I can think of and have googled.  Not sure if we need a new timer or where to go from here. I hope you can help us and we appreciate you taking the time to read/answer our question. Thank you

Hey Heather, it sounds like valve #2 is either wired to the (p) pump start or master valve terminal, or the #2 terminal is powered up each time one of the other valves is turned on, or the #2 valve is stuck on all the time. First take the wire that is hooked to the p terminal off. Now try turning on a valve, lets say valve #1. If just valve #1 comes on without valve #2, then valve #2 is hooked to the p terminal, which has power anytime another valve is on. You would need to move the wire hooked to the p terminal to the #2 terminal, and un-hook the wire currently on the #2 terminal. If valve #1 does not come on at all, then that means you do have a master valve, and you will need to put the wire back on the p terminal. The master valve is a valve that turns on water to the mainline that feeds all the other valves. If when the wire is un-hooked from the p terminal, and valve #1 does not operate, this means the reason valve #2 stays on, is either because it is stuck on all the time, and needs to be rebuilt, or the #2 terminal has power to it when all the other valves operate, and the controller needs to be replaced. To tell if it is the valve or the controller, take the wire off of the #2 terminal, turn on valve #1, and if the #2 valve comes on with the #1 valve, then the valve is defective and needs to be replaced. If the #2 valve does not come on, then the controller is defective and needs to be replaced. Good luck and have a great day.


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Jim Schaefer


Any question regarding sprinking systems,installation,repair, and trouble shooting.


I have been installing and repairing sprinkling systems since I was 15 years old. Have owned my own sprinkler system contracting business for over 26 years. It is basically the only job I've ever done, except for being a paper boy when I was young.

High School diploma and 3 years college credits.

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