Boiler will not ignite, multiple ignition attempts heard, then F.28 displayed

Safety: Turn off the boiler and check for any smell of gas. If you smell gas, shut off the gas supply, ventilate the area, and contact your gas supplier or emergency service.

User checks:

• Ensure the gas isolation valve to the boiler is fully open.
• Check that other gas appliances in the property are working to confirm supply.
• Reset the boiler according to the user manual and observe if it ignites.

If F.28 persists, a technician should:

• Check inlet gas pressure at the boiler.
• Inspect and clean the burner and injectors.
• Inspect and test the ignition electrode and cable; replace if cracked or worn.
• Test the gas valve operation and replace if faulty.

Do not attempt to dismantle gas components yourself.