Glow-worm F.29 Fault Code: Flame Loss
Hertfordshire, Bedfordshire & Cambridgeshire
F.29 on a Glow-worm is a flame loss fault. The boiler lit, then the flame went out or the boiler lost sight of it.
Different from failing to light at all, and there are genuinely useful checks you can do first.
What F.29 actually means
The burner ignited, so ignition itself is working. Something then interrupted the flame or the signal proving it.
After enough repeats the appliance stops trying and reports the fault.
What you can safely check yourself
Reset once. Repeated flame loss is a real fault.
Check the gas supply. Try another gas appliance. A supply that is marginal will light a boiler then starve it. Check credit on a prepayment meter.
Check the condensate pipe. A blocked or frozen condensate is a very common cause of a boiler lighting and dropping out, especially in cold weather. Warm, not boiling, water along the outside of the pipe usually clears it.
Check the flue terminal outside for obstruction.
If one of those was it, reset once.
When to stop, and why
If gas, condensate and flue are all fine, stop and call an engineer.
What causes it beyond the simple checks
A partially blocked condensate trap or pipe, low or fluctuating gas pressure, a dirty or worn flame sensing electrode, a flue problem causing recirculation, or a gas valve not holding a stable output. Glow-worm is part of the Vaillant Group, and the Energy range shares its fault code structure with Vaillant appliances. If you have a Vaillant showing a similar code, the equivalent page is linked below.
How Vantage can help
We are Gas Safe registered under 956889 and cover Hertfordshire, Bedfordshire and Cambridgeshire, with an emergency line answered 24 hours a day. Call us on 01462 506374. See also boiler repair and boiler servicing.
Frequently asked questions
Why does F.29 happen in winter?
Frozen condensate is the most common cold weather cause by a long way.
Can I keep resetting it?
No. Once, then leave it.
Is F.29 dangerous?
The boiler has stopped rather than keep trying, which is the safe outcome.
Related fault codes
Other Glow-worm codes: F.20 · F.22 · F.23 · F.24 · F.25 · F.27 · F.28 · F.32 · F.61 · F.75 · all boiler advice. See also boiler repair. The same fault on other makes: Vaillant F29 · Baxi E128. See also frozen condensate pipe.
In Glow-worm’s own words
The Glow-worm Energy range fault finding table lists F.29 as: Fault: Flame loss
Glow-worm use different code sets across their ranges and generations. The definition above comes from The Glow-worm Energy range fault finding table. If your boiler is a different model and the code behaves differently, check the manual for your appliance or ring us and we will tell you what it means on your unit.
When to call an engineer
If the checks above have not cleared it, the next steps are engineer work and the boiler should not be reset repeatedly in the meantime. Call Vantage Plumbing and Heating on 01462 506374. We are Gas Safe registered under 956889, the line is answered by a person at any hour of any day, and you get a price before anyone starts.
Need help today?
Call and speak to a person, any hour, any day of the year. Get a fixed price quote or call 01462 506374.
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