It depends on the vacumn breaker if it's atmospheric only you will need one on each line after the valve. If its a pressure vacumn breaker put one on before the valves and set it say 12" higher than the highest sprinkler. main difference between the two if one has two small 1/4" valves on side and atmospheric has no valves on side.

We have tried cleaning, replacing valves three times, and nothing has worked. We have 7stations. Number one stays on unless we shut off the main water line. We finally canceled it and hooked up an irrigation timer (that usually connects to a faucet.) We turn it on manually and the pipe jerks so we know it is working properly. When we turn it off, the pipe jerks so we know water is on and off but Number one is still running. We are at our wits end. Anyone out there who can give us an answer?????

Only one anti-siphon valve is needed at the very beginning of the whole system. It has to be elevated to prevent backflow. The regular manual control valve looks similar but it has the inlet and outlet ports in a straight line and does not need to be elevated. I cannot picture the valve arrangement that you have. It is necessary to glue all the fittings

oops, first I feel I must apologize to msm859 following my rant about "90-counters". I meant no disrespect to your advice. To be honest, I only very briefly skimmed through your post and didn't even catch the part where you mentioned 90s, so I wasn't trying to be rude on that point. You recommended going with larger pipe anyways and my personal gripe is with those who still use 2" pipe and then boast about avoiding 90s. Respek! Note to others: Somebody could just as easily be thinking I'm a hack for using big pipe and not worrying about 90s. We all draw the line somewhere. Jennifer: The 1.5" returns are typically branched off a 2" main return line. They go to 1.5" where they penetrate through the wall because the eyeballs (trim pieces) are that size. I'm guessing that is what your builder is intending, but I could be wrong. In a perfect world, or if you were a Kennedy or DuPont, then that main return line would be the same size as the suction, so 3" is my armchair recommendation. If it was built with 3" suction and 2.5" return, I would not really frown on that either, but I wouldn't do it myself. Well actually, that's not true because I am doing exactly that on a current project, but that's because of some other fuzzy logic and it's not that my return is downsized, but rather my suction is upsized. If your pool was built with 2.5" suction and 2.5 or 2" return, then that would probably be better than average, but you'd be amazed at how much more you'll love your pool with bigger pipes. I mentioned to somebody here before that one of the first pools I built on my own, I used a 1/2 HP filter pump on 2" pipes and I was a little disappointed that the pump did not seem to be any quieter than any of the hundreds of 3/4 HP pumps I've seen in service. So last year, I did a project of several small fountains like you might see at a ritzy shopping center (these things are more painful than any pool I've ever built), each on its own filtration system. I used 2.5" suctions and returns, reducing down as appropriate for the returns and fountain nozzles. The pipe runs were all well over 100' in each direction, two of them approaching 160', and those pumps were so quiet I was stunned and amazed. If you do go with the Intelliflo, then the Intellitouch will certainly be a nice complement to that, but you might also consider the EasyTouch. In a nutshell, the EasyTouch is a value-engineered, toned-down version of the Intellitouch. I'm not familiar enough with it to know for sure that it controls the Intelliflo in the same manner, but it's definitely worth looking into. If your builder doesn't know either, he can contact his local Pentair rep. who will be happy to lend a hand. Something else I just noticed is that they've spec'd a 1 or 2 HP Whisperflo for the two laminar jets. This equation is way out of balance because those laminars only need 10 gpm each. Even with a 1/2 HP Whisperflow, you will wind up sending the majority of its output through the bypass line, directly back into the pool. The 1/2 HP will give you 2 or 3 times the flow you need for the laminars. Laminars are delicate and fussy, it's imperative not to give them too much flow or they can be damaged. At the least, they won't work correctly with too much flow, so there is zero advantage to oversizing the pump which runs them. Additionally, they should receive filtered water, so I would put a small cartridge filter on that pump (Clean & Clear 100 or 150 is fine for the task and not much $$). You also want to have the flow to each laminar adjustable with gate valves or globe valves because they are much more suited to very fine adjustment. Most builders would use a 3-way valve or two ball valves, which can be difficult to adjust in the fine increments needed for laminars. The laminars are proposed to be lit, but I do not see a fiberoptic illuminator listed in the specs. They are available with or without color, so you'll want to be sure and clarify that with your builder. hmmmm...a couple other things off the top of my head; you might consider going with two pool lights, along the long wall on the house side so they aren't shining into the house. This is a basic thing that many others here can vouch for. Regarding the auto-fill, I may be splitting hairs at this point but I don't really like the Pentair/Letro autofill. They have a tendency to cause hammer knocking in your house plumbing because of the way they're designed. I much prefer the new autofill from Pour-A-Lid or my former favorite, MP Industries' Auto-Lev. The prices are roughly the same and these two are much easier to install, service, and live with than the Pentair/Letro version. Well this was fun. If I can help you spend any more of your hard-earned money, don't hesitate to ask. hahaha