Why Your Boiler Starts Then Stops Immediately
Many homeowners in Totton have experienced the frustration of their boiler firing up for a moment, then shutting down without providing heat. This stop-start behaviour often points to a flame sensing fault. In this article, we’ll explore what flame sensing is, common causes of faults, how you can troubleshoot basic issues, and when to call a Gas Safe engineer for professional boiler repair or maintenance.
What Is a Flame Sensing Fault?
A flame sensing fault occurs when your boiler’s control system fails to detect a stable flame after ignition. Modern boilers rely on a small sensor—often called a flame sensor or flame detection rod—to confirm that the gas has ignited. If the sensor doesn’t pick up a flame, the boiler will automatically shut off the gas supply to avoid a dangerous build-up of unburned fuel.
How Flame Sensing Works
- Ignition: The boiler sends a spark or hot surface ignition to light the burners.
- Sensing: The flame sensor monitors a small electrical current generated by the flame.
- Confirmation: If the sensor reads the current, the boiler continues the heating cycle.
- Shutdown: If no current is detected, the boiler locks out and stops heating.
Common Causes of Flame Sensing Faults
In Totton and nearby areas like Southampton, Lyndhurst, Romsey and Calmore, homeowners often face similar issues. Here are the typical culprits:
- Dirty Flame Sensor: Over time, deposits from the gas flame can coat the sensor, preventing it from detecting the flame correctly.
- Faulty Ignition Lead or Electrode: Damaged or worn ignition leads can fail to produce a stable spark, disrupting the sensing process.
- Poor Gas Pressure: Insufficient or fluctuating gas pressure affects the quality of the flame, leading to misreads by the sensor.
- Air in the System: Air pockets in the boiler or pipework can cause the burner to ignite erratically.
- Control Board Faults: A malfunctioning PCB (printed circuit board) can misinterpret sensor signals.
Troubleshooting Your Boiler
Before you schedule a professional visit, try these basic steps. Always refer to your boiler manual and follow safety instructions.
- Check Error Codes: Many boilers display a fault code. Note it and look up the meaning in your manual.
- Reset the Boiler: A simple reset can clear temporary glitches. Wait a few minutes before restarting.
- Clean the Flame Sensor: Switch off power and gas. Remove the sensor and gently clean its tip with fine emery paper. Reinstall and test.
- Inspect Gas Supply: Ensure your gas meter is on and there are no leaks. If you suspect a leak, turn off the supply and call your gas distributor immediately.
- Bleed Radiators: Air in radiators can affect system pressure. Bleed them using a radiator key to release trapped air.
When to Call a Gas Safe Engineer
If troubleshooting doesn’t resolve the issue or you’re unsure about any step, it’s time to call in a professional. A Gas Safe engineer has the expertise to diagnose complex faults, replace worn components, and carry out safe repairs. Regular boiler servicing can also catch minor issues before they lead to a heating breakdown.
Preventing Future Flame Sensing Issues
Once fixed, you can reduce the risk of repeat faults by following these tips:
- Arrange annual boiler servicing with a qualified engineer to keep components clean and functioning.
- Monitor your system pressure and top up if it falls below the recommended level.
- Keep the boiler environment clear of dust and debris.
- Consider upgrading an older boiler to a new, more reliable model. A new boiler installation may offer improved flame detection technology and energy efficiency.
- Take out a comprehensive boiler cover plan to protect against future repairs and emergency call-outs.
Frequently Asked Questions
- Q: What does error code 318 mean?
A: On many boilers, code 318 indicates a flame loss or sensing fault. Check your manual for model specifics and try cleaning the sensor.
- Q: Can I fix a flame sensing issue myself?
A: You can perform basic tasks like resetting the boiler or cleaning the sensor, but complex repairs should be left to a Gas Safe engineer.
- Q: How much does a Gas Safe engineer call-out cost?
A: Costs vary, but many plans include call-outs. Annual cover plans can save you money on emergency repairs.
If you need help with your heating or boiler, our local engineers are here to help. Call us on (01420) 558993 or book online at embassygas.com/book.
Written by Embassy Gas — your local heating experts covering Totton, Southampton, Lyndhurst, Romsey and surrounding areas.