Just started my system for the year. Operates normally. Noticed a constant tapping in my water main (only when sprinkler supply valve is open). Kinda driving me crazy, but I'd like to water my lawn. There is a pressure reducing valve on the main line to the house but the sprinkler main is tapped in prior to the regulator. The sprinkler supply valve is a vacuum breaker type AND there is a backflow preventer further down the line (why? I don't know). Ideas? Thanks
