Boiler ignites with a loud bang or pop (hard ignition).

Safety: Hard ignition can stress the flue and heat exchanger. Turn off gas and power and have the boiler inspected by a qualified technician.

• Check flue and air supply: Ensure the flue terminal and air intake are unobstructed.
• Inspect ignition electrodes (technician): Verify correct gap and position relative to the burner as per CTC specifications. Clean or replace electrodes if worn.
• Clean burner (technician): Remove and clean the burner to ensure all ports are clear.
• Measure gas pressure (technician): Confirm inlet and burner pressures are within CTC limits. Adjust or replace the gas valve if necessary.