Pipe Hammer During Zone Transition: Zone 5 to 6 Shakes Pipes

Individual zones run fine, but during the automatic sequence, pipes shake violently only when transitioning from zone 5 to zone 6. The vibration caused water to leak from an overhead bathroom fan 10 feet away and 10 feet higher.

Cause: Pressure Surge (Water Hammer)

The sudden valve closure/open transition creates a pressure wave. Zone 5's valve may close before zone 6 opens fully, or the flow change is too abrupt.

Fix: Adjust Flow Controls

1. On each irrigation valve, open the flow control stem fully.
2. Close it fully, counting turns.
3. Reopen to half the counted turns (50% position).
4. This slows valve actuation, dampening the pressure surge.

Bathroom Fan Leak

The fan leak is likely unrelated to sprinkler pipes. Vibration may have disturbed a loose plumbing joint, HVAC condensate line, or roof flashing above. Inspect the fan housing and surrounding plumbing immediately—water damage escalates quickly.