Control valve will not shut off
My sprinkler system (toro valves) has 8 zones. everything operates normally up to zone 5. When zone five finishes and zone 6 comes on, zone 5 fails to shut off. When zone 6 shuts off so will zone 5 leaving zones 7 and 8 to operate normally. Any suggestions on what will cause this problem? The system was installed in 1997.
I suspect the problem could be
(1) the valve diaphragms are failing in the valve that controls zone 5 I also found out the valves I have are no longer made (flo pro 2800514). Will another model Flo pro valve diaphragm work? Or do I have to replace the valve manifold or
(2) the timer could be causing the problem. If it were the valve causing the problem why would it shut off after zone 6 finishes in theory it should continue to run with all the zones.
Any Suggestions?
Rich