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

Hello,
I'm having issues with my sprinkler system. When the system turns on it will start hammering (extremely loud and fast on house water line). The only way to stop it is to turn the water off or turn the sprinkler system off. When the hammering starts water is coming out the anti siphon. I've put a new siphon on, and added a backflow valve below it. Ive cleaned around the valves and took 7 of 8 valves apart and cleaned. All this work has not fixed the issue? Any help would be appreciated.

Yes, its using a control box.
Ok, I tried reducing the amount of water used for each zone by changing out all the rotor sprayers with Rainbird professionals 5000 using a 1.5 gpm nozzle (down from the standard 3 gpm). We then cut out the 8 valve manifold and built our own. We used rain bird valves. When removing the old manifold we found on the end of the "T", buried in the dirt, a little drain with screen. I was surprised because looking more closely at this, it looks like a really small check valve (small little spring inside). Which allows the manifold to drain when there's no water pressure. After doing all this work, were still getting really bad water hammer. I can't tell you how frustrating this is. I built our new manifold the same as the old one and reused the little drain check valve. Do you think this could the reason for all the water hammer?
Tomorrow, I'm going to check the output power from the controller as suggested. Thanks for your help.

Ok, I opened the zones manually, by turning the bleed screw open, and almost every zone would hammer. How do I check the voltage for 24v from the transformer?
There are 8 zones and the majority have 4 rotors with 1.5 gpm nozzles. I have one zone that is for the flower beds and its using 8 pop up sprayer (not rotors).
I'm going to attach pictures of the system. Also have called my irrigation district to have them come check my pressure, flow rate, and back flow.
Ive changed everything but the control box, which is a Rachael (Turf products Division) 508PR
The hammer is so loud it shakes my floors and makes my dog go nuts. I noticed no water is flowing through the city main valve when this is happening.

Another note: Ive registered for this site, but can't complete registration. It never sends me the email with activation code. Ive tried other emails with same result. This needs to be fixed for pictures, I think.
Thanks

The problem has been found. I changed out the wiring from the contr4ol box to the valves. While I was removing the old wire ( it ran up from my basement between the rafters to outside), we found a spot on the wire where it had rubbed through and was intermittently contacting the staple. Once the new wire was put in the problem stopped. We think the short was causing the valve to open and close randomly.