Error A10, unit may start but then shut down, sometimes with fluctuating temperature readings.

Safety: Turn off power before accessing the control board or sensors.

• Locate primary NTC: Find the flow temperature sensor clipped to the primary heat exchanger outlet pipe.
• Check connection: Ensure the plug is fully inserted into the sensor and the control board. Look for corrosion or moisture on the contacts.
• Inspect cable: Follow the cable for cuts, pinches, or burn marks. Replace if damaged.
• Sensor replacement: If the sensor body is cracked or readings are clearly wrong (e.g., showing very high or low temperature when cold), replace the NTC sensor with the correct Fondital spare.
• Control board: If a new sensor does not resolve A10, the temperature input circuit on the control board may be defective and requires professional replacement.