Glow-worm F.27 Fault Code: Fault in Flame Detection
Hertfordshire, Bedfordshire & Cambridgeshire
F.27 on a Glow-worm is a safety switch-off caused by a fault in flame detection. The boiler is seeing a flame signal when there should be none.
This is one to leave alone. Turn the boiler off and get an engineer to it rather than resetting it.
What F.27 actually means
When the burner is off, the flame sensor should report no flame. If it still reports one, the boiler cannot tell whether gas is genuinely burning when it should not be, or whether the sensing circuit is giving a false reading.
Both possibilities are treated as serious, so the appliance locks out.
What you can safely check yourself
Do not reset this repeatedly and do not leave it running.
Nothing. There is no homeowner check that helps and the components are inside the appliance.
Turn the boiler off at the switch and call a Gas Safe engineer.
When to stop, and why
Stop now. This is not a reset-and-see code.
What causes it beyond the simple checks
Most commonly a failed or contaminated flame sensing electrode giving a false reading, or moisture on the electrode. Less commonly a gas valve that is not closing fully, which is the reason this fault is treated seriously. 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
Can I use my boiler with F.27 showing?
No. Turn it off and call an engineer.
Is F.27 dangerous?
The switch-off is the boiler being safe. The reason behind it needs diagnosing.
Is it usually the electrode?
Often, yes. But it cannot be assumed, because the alternative involves the gas valve.
Related fault codes
Other Glow-worm codes: F.20 · F.22 · F.23 · F.24 · F.25 · F.28 · F.29 · F.32 · F.61 · F.75 · all boiler advice. See also boiler repair. The same fault on other makes: Vaillant F27 · Worcester Bosch FA · Ideal L6.
In Glow-worm’s own words
The Glow-worm Energy range fault finding table lists F.27 as: Safety switch-off. Fault in flame detection
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.
Need help today?
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