Heater frequently reaches set temperature then overshoots or undershoots before cycling.

Safety first: Turn off power before relocating sensors or adjusting plumbing.

Steps to reduce overshoot/undershoot:

• Verify sensor location: Ensure the Raypak water sensor is installed in the heater header as designed, not in a remote tee with stagnant water.
• Improve mixing: Adjust return fittings or plumbing to promote better mixing of heated water with pool water.
• Adjust setpoint strategy: For spas or small pools, use smaller setpoint changes and allow time for temperature to stabilize.
• Automation integration: If using automation, ensure it is not fighting the heater’s internal control (avoid double control loops).

Note: Some cycling is normal; extreme overshoot may indicate sensor or control issues.