The short version
- Write the code down exactly before you reset anything
- One reset is reasonable, a repeating code is a diagnosis job
- Most Glow-worm lockouts protect the appliance rather than indicate it is beyond repair
- Never open the casing or touch gas components yourself
How the code groups work
Low numbers are sensor faults, the twenties cover water content and ignition, and the seventies cover pump and pressure sensing. A code that appears only when the heating starts from cold usually points at ignition or condensate rather than electronics.
The codes we see most often
These are the ones that come up week to week on Glow-worm appliances around Wigan and Leigh, with what each one usually means in practice.
- F1: no flame detected after ignition attempts.
- F22: low water content in the appliance, normally genuine low pressure.
- F28: ignition failure at start up.
- F75: no pressure change when the pump runs, so pump or sensor.
- F13 or F20: overheat or sensor fault requiring testing.
Older Glow-worm appliances and parts
Glow-worm has a long back catalogue and plenty of appliances in Wigan housing are well past a decade old. Parts availability drops off on discontinued ranges, so on an older unit the honest conversation is whether a repair buys enough time to be worth it. We will tell you what has failed, what it costs and what is likely to fail next rather than quietly steering you toward a replacement.
What you can safely check yourself
There is a small set of checks any homeowner can make before calling out an engineer, and none of them involve the boiler itself.
- Pressure gauge reading against the marked band
- Whether other gas appliances in the house are working, which tells you about supply
- Whether the condensate pipe outside is frozen in cold weather
- Thermostat batteries, timer settings and whether anyone has changed them
Where the line is
Never remove the boiler casing, adjust gas controls or work on any gas component yourself. Those are Gas Safe engineer jobs by law. If you smell gas, call the National Gas Emergency Service on 0800 111 999 and turn the gas off at the meter.
Common questions
Are Glow-worm and Vaillant codes the same?+
They are similar because the platforms are related, but not identical. Always quote the make and model as well as the code.
What causes F22 to keep coming back?+
Pressure dropping again after a top up means water is leaving the system. Find the leak rather than refilling repeatedly.
Can I still get parts for an old Glow-worm?+
Sometimes. Availability on discontinued ranges is patchy, so we check before recommending a repair.
Is a Glow-worm worth repairing?+
It depends on age, the part that has failed and the condition of the rest of the system. We give a straight answer rather than a sales pitch.
Glow-worm fault code showing?
Tell us the model and the exact code and we will bring the likely parts with us rather than diagnosing blind.