Burner does not ignite, display shows A01 shortly after a hot water or heating demand.

Safety first: Turn the Fondital water heater OFF, close the gas cock, and disconnect power before removing any covers. If you ever smell gas, ventilate the room immediately and call a qualified technician or gas supplier.

• Check gas supply: Verify the main gas cock to the heater is fully open. Confirm other gas appliances in the home work. If not, contact your gas provider.
• Reset the appliance: Use the reset button on the control panel (refer to your Fondital model manual). If A01 clears and the unit runs normally, monitor for recurrence.
• Inspect ignition electrode: With power OFF and front cover removed, visually inspect the ignition electrode near the burner. Look for cracks, heavy oxidation, or loose connections on the high‑voltage cable. Clean light deposits with a non‑metallic abrasive pad.
• Check flame sensor (ionization electrode): Ensure the electrode tip is correctly positioned in the burner flame area and the cable is firmly connected to the control board. Clean gently if sooted.
• Gas valve and pressure: If gas supply is present but ignition still fails, the gas valve or its coil may be defective, or gas pressure may be out of spec. This requires a qualified Fondital service technician with manometer and combustion tools.

Do not repeatedly reset a unit that fails to ignite; unresolved ignition faults can be dangerous.