I have an 8-zone, in-ground sprinkler system. There is a 1″ copper pipe that comes out of the ground next to the house with an anti-backflow valve at the top. Then it goes back into the ground. Just before the pipe goes into the ground, there is an automatic drain valve which I believe should only open once the water is shut off and the pressure decreases. I assume this is the supply for the entire system. This system has been working well for years, but a couple of days ago it stopped.
I tried using the electronic wall controller to run it manually to see what the problem was, but none of the zones produced water. But what does happen is when the zone is turned on, water starts to dribble out of the automatic drain, and then turns into a strong flow which continues until the zone is shut off. Nothing comes out of the sprinkler heads, although I can feel a vibration in the shutoff valve for the zone being tested so I believe the valves are opening as they should.
I am not aware of any shutoff valve on the supply side of the sprinkler system. At any rate the system has been running fine and has not been touched until the water stopped flowing recently.
This doesn’t make sense to me. I would have thought the pipe going thru the anti-backflow valve would always be at normal house water pressure, so I am not clear on why there is an automatic drain on it. I would think this would mean a valve on the supply before going into the anti-backflow valve. I am stumped.
Any of you plumbers or sprinkler guys out there have any ideas?