Water temperature fluctuates widely or overshoots the set temperature.

Safety: Overheating can be dangerous; monitor water temperature with an external thermometer.

• Verify with thermometer: Compare displayed temperature to an independent thermometer to confirm actual water temperature.
• Check circulation: Ensure the circulation pump runs as programmed and that there is good flow past the heater and sensor.
• Inspect sensor seating: Confirm the temperature sensor is fully inserted into its well and making good thermal contact.
• Replace sensor: If readings are erratic, replace the Hydropool temperature sensor.
• Board issue: If the heater continues to run past the setpoint with a good sensor, the heater relay or control logic may be faulty and require board replacement.