Question
I have 8 zones on my system with an Irritrol controller.  1-4 serve the backyard and 5-8 the front.  The system has been functioning well for two years.  

The problem: Anytime another zone is activated either manually or automatically, zone 7 comes on and runs the full time the other zone is on.  I disconnected the wire for zone 7 at the terminal block and nothing will come on while disconnected.

I have looked for loose connections at the valve and controller but nothing is obvious.  The valve for zone 7 still functions well, i.e. no seepage and opens and shuts well.  It just comes on no matter which valve is receiving current. I have adjusted the time setting to valve 7 to OFF and it has no effect on the situation.

Answer
How many stations does your timer hold?

Have you tried to put zone 7 wire into another terminal and to see what happens?

It seems like it is acting like a Master Valve and if the wire is not connected to the MV/COM terminals then it would seem like the zone 7 terminal is malfunctioning.


Please reply when you have a minute.