QuestionI have a 3 zone irrigation system with Hunter heads with a rain bird ESP-6tm control panel. The first two zones work fine and make no knocking sounds. The pressure runs around 45-50. When the third zone starts up the pressure drops to around 30-35, makes a knocking sound as it builds up the pressure back to 45-50 and the cycle repeats. When I look at the Watt Series 800M4 Anti-Siphon Pressure Vacuum Breakers during the knocking, water spurts out of the top of the system. When the irrigation system is completely off, there is a very small drip but nothing large from the anti-siphon pressure vacuum breaker. I noticed there was a head leaking in the zone that seems to be losing pressure, so I changed the head, but it continues to knock, but only in zone 3. Any suggestions would be greatly appreciated.
AnswerPlease explain the 3 zones in detail. Which part of the property they cover. What type of heads are on them. Is there any elevation change among the zones. What is the elevation difference from that backflow to the lowest or highest head on zone 3? Is the noise more of a thumping or a loud banging. Do you have hardwood floors or stone in the home?
