SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

I am experiencing a strange problem with my sprinkler valves that I suspect has to do with my high water pressure of 90psi but I am not completely sure. If someone with more plumbing smarts than me could verify my suspicion it would be much appreciated. Last year before shutting my sprinkler system down for the winter I was running 60psi and was not having any issues. The major symptom I am experiencing now is continuous water hammer (or is it water surge not sure about the terminology) that will not stop once any one of my sprinkler valves are opened and then closed. Let me stress the point of "the water hammer will continue on forever" and its loud and very noticeable shaking all of my valves and causing my sprinkler heads in that zone to pop up and down. I then must shut the main valve off to my sprinkler valves so my valve can completely close and then I can once again turn the water back on and the water hammer will be gone. But as soon as I try and open any valve to water and then close it the water hammer starts again, it doesn't matter the valve they all do it. It also doesn't matter if I open the valves manually or use the controller. I suspect that the sprinkler system tee's off before the pressure regulator I have under my house. The sprinkler valves I am running are Rainbird JTV-100 valves that according to the manufacturer can handle up to 150PSI so they should be able to open and close without issue under 90psi. I have since tried unhooking the sprinkler wires from my controller just to make sure it isn't a wiring problem.

Thanks for any help!