Since you're using anti-siphon valves, I assume you don't have a backflow prevention device between your valve manifold and your main supply line. The anti-siphon feature of your valves is intended to prevent possibly contaminated water from being sucked back into the main line. This method of backflow control is now generally viewed with disfavor, and may not comply with applicable codes. If the valve is not positioned at the mandated height above the sprinkler or drip line, the anti-siphon feature is defeated. On the bright side, a simple $10 backflow preventer is usually all that is required for a soaker hose or drip line, and when you open the valve, the water will flow. You will also need an inexpensive pressure regulator. Putting this together may be a bit tricky, and you will need to bear in mind the incompatibility of hose threads and pipe threads as you select the requisite components.

Never mind. Just talked to a co-worker with the same problem and he indicated that a sprinkler installer recommended using funny pipe/ez-tube to lower his heads. I'm going to give this a try.

In-ground boxes were used; however, they were overgrown with grass. We finally managed to locate all 7 zone valves and the master valve. It only took about 10 hours, but we found them all, and cleaned them out. That was 80% of the time spent on this project. Lesson learned...keep those valve cover areas weedeated out every week!! The root cause appears to be sand from our well. We get this really fine sand from the Paluxy Sands in our well water. We had severe sand issues for a while after first digging the well, and apparently it was enough to cause problems in the irrigation system 3 years later! The sand got into the diaphragms in the valves and blocked the little pin holes that allow the valves to close. That, combined with lowering the water pressure slightly, would not allow the valves to close. Thus, multiple stations would be running at the same time. Everything is working better than before now, thank goodness! I found a great site for electrical troubleshooting that helped a lot (link below); that helped narrow down the possibilities right off the bat. Here is a link that might be useful: Sprinkler System Electrical Troubleshooting

Hi HW, I am a little puzzled by your description. To clarify I need you to answer some basic questions. 1. Is your system new? 2. Was it installed by Hydro-tech the irrigation company that installs name brand system components? 3. What brand and model is your controller? 4. How many zones (auto-valves) in your system. 5. What duration is the zone set for? The controller should read how much time is left watering the zone. Does this go to zero and the valve doesn't stop irrigating? What does the controller show when this happens? It seems to me, and you can set me straight on this,that if there is a problem, it may be in the controller. Spanking the valve is never a good thing and probably caused the solenoid to shut the zone down prematurely. The valve is not the brains of the system, the controller is. JMHO Aloha