How to Fix Main Combi 24 HE Flame Failure?

What Causes Main Combi 24 HE Flame Failure?

A flame failure on a Main Combi 24 HE can be caused by several technical faults. The most common include:

Faulty Rectification Electrode

The rectification electrode confirms that a stable flame is present. If it fails to detect the flame correctly, the boiler can shut off the gas supply as a safety measure.

Faulty Ignition Electrode

A worn or faulty ignition electrode may fail to produce the spark needed to ignite the burner.

Gas Valve Problems

The gas valve controls the flow of gas to the burner. A faulty valve can prevent enough gas from reaching the burner, causing ignition problems or flame failure.

PCB Faults

The printed circuit board controls functions including ignition and flame detection. A faulty PCB can therefore cause intermittent flame failure and other ignition-related problems.

Fan or Air Pressure Switch Problems

The fan provides the airflow needed for combustion. If the fan is weak or faulty, or the air pressure switch fails to confirm sufficient airflow, the boiler may prevent ignition as a safety measure.

Other Possible Causes

• A blocked flue affecting airflow
• Low water pressure
• A frozen condensate pipe during colder weather

How to Diagnose and Fix Main Combi 24 HE Flame Failure

If you are a qualified Gas Safe heating engineer, diagnosing the fault involves working through the boiler's operating sequence and checking the relevant components.

Observe the Boiler's Operation

A typical sequence is: the boiler detects a demand for heating or hot water; the fan starts and the air pressure switch signals the PCB; the ignition electrodes receive voltage and produce a spark; the gas valve opens and the burner ignites; the rectification electrode confirms that a stable flame is present.

If the boiler fails to ignite while the fan is running and there is no sparking sound, the fault may be occurring after the fan has started.

Inspect the Key Components

• Air pressure switch: confirm that it is signalling correctly after the fan starts.
• PCB: check for visible damage and abnormal signals. Intermittent faults can be caused by PCB failure.
• Gas valve: check that it is operating correctly and that sufficient gas is available.
• Ignition and rectification electrodes: inspect for wear, damage and poor connections.

Carry Out the Necessary Repairs

The repair will depend on the confirmed fault. This may involve replacing a worn or faulty electrode, repairing or replacing a faulty gas valve, replacing a failed PCB or repairing damaged soldering where appropriate, or investigating poor fan performance and replacing a defective air pressure switch.

Do not repeatedly reset the boiler if the flame failure keeps returning. Arrange for a Gas Safe registered engineer to investigate the fault.

Test the Boiler

After the repair, the boiler should be tested to confirm that it ignites consistently and completes its operating cycle without the flame failing.

If you are not Gas Safe registered, do not attempt to repair these components yourself. Boiler faults involving gas and combustion should be handled by a qualified engineer.

If You Smell Gas

If you smell gas at any point, stop immediately. Do not attempt any of the diagnostic steps above, and do not operate light switches or naked flames. Turn off the gas supply at the meter if it's safe to do so, ventilate the area, and call the National Gas Emergency Service on 0800 111 999 straight away.

Why Is Regular Boiler Servicing Important?

Regular boiler servicing can help identify worn components and developing faults before they lead to a breakdown.

During a service, a Gas Safe engineer can check for signs of wear, inspect gas pressures and system performance, and assess key components such as the burner and electrodes. The boiler's safety mechanisms and flue can also be checked.

Regular servicing can help maintain safe and reliable boiler operation and may reduce the risk of unexpected breakdowns.

Professional Main Combi Boiler Repair

If your Main Combi 24 HE is showing a recurring flame failure, professional fault diagnosis is the safest option.

Serviceteam provides boiler repair services for faults that require professional diagnosis and repair. An engineer can identify the underlying cause rather than repeatedly resetting the boiler without resolving the fault.

Contact Serviceteam to arrange a boiler repair if the flame failure continues or your boiler is not operating normally.

Key Takeaways

A Main Combi 24 HE flame failure means the boiler has failed to ignite or maintain a stable flame.

Common causes include:

• Faulty ignition or rectification electrodes
• Gas valve problems
• PCB faults
• Fan or air pressure switch problems
• Flue, pressure or condensate issues

Repeated flame failures should not simply be reset. A Gas Safe registered engineer should diagnose the underlying fault and carry out any necessary repair.

Frequently Asked Questions - (FAQs)

If your Main Combi 24 HE is showing a flame failure fault, usually indicated by the middle LED flashing, you can try resetting the boiler: turn the selector switch fully anti-clockwise to the Reset position — you should feel spring resistance — hold it there for at least two seconds, then release the switch and allow the boiler to restart.

If the flame failure returns, do not keep resetting the boiler. Arrange for a Gas Safe registered engineer to investigate the cause.

A flame failure means the boiler has been unable to ignite or maintain a stable flame. Possible causes include ignition faults, gas valve problems, flame detection faults, airflow problems or other component issues.

A qualified Gas Safe engineer should diagnose the cause rather than repeatedly resetting the boiler.