I have a friend that has decided to install a sprinkler system. Since I have installed a couple, I designed one for his yard and was out to buy all the parts for it today. I noticed that Rain Bird is only selling in-line valves in stores around here. I have always installed the above ground anti-siphon valves just due to the fact that if I need to work on them, they are more easily accessible without having to lean down in a hole. So ny question is why did the anti-siphon valves disappear and what makes the in-line valves the way to go?
Different states have different rules about this. Here in PA, we can use a double check valve (an in-line valve), but in NJ the law calls for a pressure vacuum breaker, which is probably safer. If you use a PVB it should be installed at least 1' higher than the elevation of the highest sprinkler.