Water heater does not ignite; display shows error 01 shortly after a call for hot water or heating.

Safety first: Turn off electrical power to the water heater and close the gas isolation valve before removing any covers. Allow the unit to cool fully.

Steps to check:

• Reset the appliance: Restore power, open the gas valve, and press the reset button as per the Biasi manual. If error 01 reappears, continue below.
• Inspect the burner area: Remove the front cover. Check the main burner for dust, rust flakes, or debris. Gently vacuum and clean with a soft brush. Do not use water or solvents on the burner.
• Check the ignition electrode: Look for cracked ceramic, loose connections, or heavy carbon deposits. Clean the tip with fine emery cloth and ensure the electrode gap and position match the Biasi specification. Reseat the ignition cable firmly on both ends.
• Check the flame sensor (ionisation probe): Clean the probe with fine abrasive pad, ensuring it is positioned in the flame path. Inspect the cable for damage and ensure a tight connection to the control board.
• Verify gas supply: Confirm the gas isolation valve is fully open and that other gas appliances in the home work correctly. If gas supply is suspect, contact your gas supplier or a licensed gas technician.

When to stop: If the unit still shows error 01 after cleaning and checking visible components, or if you smell gas, stop immediately and contact a qualified Biasi service technician.