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water hammer
installed a rainbird system and used auto-drains at the end of each zone. Are they the cause of my water hammer when the zone valves open and close??
I would seriously doubt it. I'd start with pressure and flow back at the beginning.
But we don't use auto-drains down here so I'd wait for one of the pros to chime in.
Empty zone lines could lead to pipe-banging when a zone opens, if the system design is bad to begin with. But true water hammer is when a zone valve slams shut, and auto-drains aren't a part of that phenomenon.