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Water gushes out from the anti-siphon cap and then stops
I installed five Rain Bird anti siphon valves about 20" higher than the highest sprinkler head. They share the same supply line and shutoff valve. The water pressure is 80 psi. I know it's too high.
Four of the five valves work perfectly. After turning off the valve, water gushes out from the anti-siphon cap of the fifth valve for a few seconds and then stops.
I want the valve to operate completely dry. I would appreciate it very much if you could tell me what I should to make the fifth valve work like the other four valves.
There really isn't anything practical that you can do about that water, as it comes from the spring-loaded sprinkler heads pushing some water backwards, while the heads retract. Different sprinkler heads would have to be installed. Or maybe only one different head, just so that at least one head would gush water around the 'wiper seal' during retraction.
In olden days, all spring-loaded heads would gush water as they popped down, because the seals were simpler than they are today.
Thank you very much your inputs. The fifth zone do have two spring-loaded sprinkler heads. But zone 1-4 also have spring-loaded sprinkler heads. Any idea why water gushes out only from the anti-siphon cap of the fifth valve?
Not from the information you provided. In any event, this 'flow-back' has been known about for decades, and the anti-syphon valves are still code-approved.
You are absolutely right! After I replaced the two spring-loaded sprinkler heads with regular heads in zone 5, no water gushes out from the anti-siphon cap of the fifth valve any more. Now water gushes out from the anti-siphon cap of the 3rd valve because there are two spring-loaded sprinkler heads in zone 3. I will replace them with regular heads tomorrow.
There are no spring-loaded sprinkler heads in zone 1 and 2. There are spring-loaded sprinkler heads in zone 4. But they are located downhill. So I don't expect the same problem in that zone.
Thank you very much for your help!
You might complete the experiment by switching back one head, and see what results. This isn't strictly about the spring-loading, but about whether the heads can gush water when they are not completely popped up. (sometimes called "flow-by")
strange thing happened. After I replaced the two spring-loaded sprinkler heads with regular heads in zone 3, water not only gushes out from the anti-siphon cap of the 3rd valve, but also from the 5th valve again. Any ideas?
How many hundreds of dollars are you willing to spend to make this go away?
Do inline sprinkler valves have the same problem?
They do not. That's where the hundreds come in. Install a Pressure Vacuum Breaker, along with underground valves, and no water exits anything but the sprinkler heads.