Glow-worm F29 Fault Guide for Homeowners: Meaning, Symptoms, Actions, Costs, Causes, Prevention
The Glow-worm F29 fault code indicates that your boiler has locked out due to a flame detection failure during operation. The main symptoms are: your boiler shuts down unexpectedly, shows an F29 error, and fails to produce heat or hot water. To resolve this issue, you need to attempt a boiler reset, but if the fault persists, professional assistance is required. Repair costs vary, ranging from £80 for a reset to £300 or more if key components such as the flame sensor or gas valve require replacement. The most common causes of this fault include low gas pressure, a faulty flame sensor, a blocked condensate pipe, or ignition failure.
Preventative measures include:
- Annual servicing.
- Keeping the condensate pipe clear.
- Ensuring a stable gas supply.
Always use a Gas Safe-registered engineer for any repairs, as gas-related work requires professional expertise. The next section will explain the meaning of the F29 fault in more detail.
Meaning of the Glow-worm F29 Fault
The Glow-worm F29 fault code appears when the boiler detects an interrupted flame signal, causing it to shut down for safety. This means the burner has ignited but failed to maintain a stable flame, which prevents the boiler from operating correctly. The fault occurs when the flame sensor cannot detect a steady flame or when the ignition process is disrupted. A temporary reset may clear the issue, but repeated faults indicate a deeper problem.
What does the F29 fault code indicate on a Glow-worm boiler?
The F29 fault code means that your boiler has lost the flame signal during operation, leading to a lockout for safety reasons.
Why does my Glow-worm boiler display the F29 fault?
Your boiler displays the F29 fault when it fails to detect a stable flame, often due to low gas pressure, a faulty flame sensor, or ignition failure.
Is the F29 fault dangerous?
The F29 fault itself is not dangerous, but it prevents the boiler from working. If caused by gas pressure issues or a blocked flue, it could lead to further safety risks.
Can I fix the Glow-worm F29 fault myself?
You can attempt a simple boiler reset by pressing the reset button. If the fault returns, further diagnosis by a Gas Safe engineer is necessary.
Will the F29 fault reset itself?
The F29 fault does not reset itself. The boiler requires manual intervention to attempt a restart.
What happens if I ignore the F29 fault?
Ignoring the F29 fault means your boiler will not function, leaving you without heating or hot water. Repeated ignition failures can also damage internal components.
The next section will describe the symptoms of the F29 fault in more detail.
Symptoms of the Glow-worm F29 Fault
The Glow-worm F29 fault prevents the boiler from maintaining a flame, causing it to shut down unexpectedly. You may notice that your boiler stops producing heating and hot water. The display screen will show the F29 error code, and you may hear repeated clicking noises as the boiler tries to ignite. If the fault is linked to gas supply issues, other gas appliances in your home may also stop working.
How To Recognise The Glow-worm F29 Fault on Different Types of Boilers
Glow-worm Combi Boilers
Combi boilers will display F29 on the digital screen, indicating a loss of flame signal. The boiler will not provide hot water or heating, and it may attempt ignition multiple times before shutting down.
Glow-worm System Boilers
System boilers show the F29 fault code on the control panel. You may notice that the heating system remains inactive, with the water pressure gauge staying unchanged.
Older Non-Digital Boilers
Older Glow-worm boilers without digital displays do not show error codes. Instead, the boiler may shut down unexpectedly, and the reset button may flash or require pressing to restart.
The next section suggests actions to take in the event of the F29 fault.
What to Do When Your Glow-worm Boiler Shows the F29 Fault
When your Glow-worm boiler displays the F29 fault code, the first step is to attempt a manual reset by holding the reset button for 3–5 seconds. If the boiler reignites successfully, monitor it to see if the fault returns. Check whether your gas supply is working by testing other gas appliances, such as your hob. If your appliances also fail, the issue may be with your gas provider rather than the boiler.
If the fault persists, turn off the boiler and contact a Gas Safe engineer. Do not attempt to open the boiler casing, adjust the gas supply, or repair internal components, as this requires professional expertise.
Safety Warning
Only perform actions described in your boiler’s user manual. Do not attempt to dismantle the boiler or adjust gas-related components. A Gas Safe-registered engineer must handle any further repairs. If you smell gas, turn off the gas supply at the meter, open windows, and call the emergency gas helpline.
How do I reset my Glow-worm boiler after an F29 fault?
Press and hold the reset button for 3–5 seconds. If the boiler restarts, monitor it for further faults.
Should I turn off my boiler if it shows the F29 fault?
If the fault persists after a reset, switch off the boiler and call an engineer. If you smell gas, turn off the gas supply immediately.
Where is the reset button on my Glow-worm boiler?
The reset button is located on the boiler’s front panel, usually near the display screen.
Can I fix the F29 fault myself?
You can reset the boiler and check for external issues such as gas supply problems. Any further repairs require a Gas Safe engineer.
The next section will describe the cost to repair Glow-worm F29 Fault in more detail.
Cost to Repair Glow-worm F29 Fault
The cost to repair the Glow-worm F29 fault depends on the cause of the ignition failure. The minimum repair cost for a basic reset or minor adjustment starts at £80–£100. If the issue involves gas pressure adjustments or condensate pipe clearing, you can expect to pay between £100–£200.
If faulty components require replacement, costs increase. A new flame sensor or ignition electrode typically costs between £150–£250, including parts and labour. A faulty gas valve replacement ranges from £250–£400, depending on the model and installation complexity.
In rare cases, if multiple parts fail or your boiler is old, a full boiler replacement may be recommended. A new Glow-worm boiler installation costs between £1,500–£3,000, depending on the model and labour charges. Getting multiple quotes from Gas Safe engineers ensures you receive a fair price. A boiler cover plan can help reduce unexpected repair costs.
The 5 Major Causes of the Glow-worm F29 Fault
The Glow-worm F29 fault is caused by flame detection failure, which prevents the boiler from operating. The most common causes include low gas pressure, a faulty flame sensor, a blocked condensate pipe, ignition failure, and a defective gas valve.
1. Low Gas Pressure
Low gas pressure prevents the flame from stabilising, causing the boiler to shut down. Supply issues, a partially closed gas valve, or frozen external gas pipes can all lead to this problem.
2. Faulty Flame Sensor
The flame sensor detects whether the burner is active. If it is dirty, misaligned, or defective, the boiler cannot confirm ignition, causing the F29 fault.
3. Blocked Condensate Pipe
The condensate pipe removes acidic wastewater. If it becomes frozen or blocked, the boiler may fail to maintain a flame, leading to a shutdown.
4. Ignition Failure
A worn-out ignition electrode may fail to produce a strong spark, preventing the boiler from lighting correctly.
5. Defective Gas Valve
A stuck or faulty gas valve disrupts fuel flow, leading to ignition failure. A professional inspection is required for repairs.
The next section will explain how to prevent this fault from occurring.
Preventing Future Glow-worm F29 Faults
Annual boiler servicing ensures that gas pressure, ignition components, and sensors function correctly. A boiler service contract includes regular inspections and emergency callouts, reducing the risk of faults. Keeping the condensate pipe clear and ensuring a stable gas supply also helps prevent the F29 fault.
Disclaimer
Only a Gas Safe-registered engineer should repair internal boiler faults. Do not attempt to dismantle the boiler or adjust gas components. Always follow the manufacturer’s manual for safe operation.