Thermona Delayed Ignition / Gas-Air Mixture Issue

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

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Incorrect gas valve adjustment on Thermona boiler, Dirty or partially blocked burner, Weak ignition spark, Low gas pressure at appliance

Safety: Delayed ignition can stress the combustion chamber and flue. Do not ignore repeated banging on ignition.

Stop using boiler: If bangs are frequent or loud, switch off the boiler and do not use it until checked.
Engineer inspection: A Thermona technician should clean the burner, check and adjust gas valve settings, verify ignition electrode condition and gap, and confirm gas supply pressure.

Professional Required 5/5

Burner Assembly

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