My Irrigation System (6 Zones with Hardie RD-600 Controller) are innitially "hammering across all 6 zones" for about 5-8 seconds when either in auto or manual mode. The system is about 10-12 years old and I did'nt initially have this problem. The street water pressure is about 55 - 65psi. I believe the valves are also "Hardie". I will check to see model nos. Possibly..... Does the diaphrams / solinoids need replacement to correct this chatter???? The piping in the basement really chatters at startup across all zones. I appreciate your advise!