Pump runs but there is a loud water hammer or banging noise in the plumbing when it starts or stops.

Safety first: Turn off power before adjusting valves or plumbing.

• Slow valve operation: Open and close valves slowly to reduce sudden changes in flow.
• Adjust speed ramps: On variable-speed Hayward pumps, increase ramp-up and ramp-down times to soften starts and stops.
• Inspect check valves: Check any installed check valves for proper orientation and operation. Replace if they slam shut.
• Bleed air: Ensure the system is fully primed and air is purged from high points in the plumbing.