Glow-worm boilers show faults as F. followed by a number. Older Glow-worm boilers use different numbers: F9 on older models matches today's F.22, and F1 matches F.28 or F.29.
Glow-worm says F.22 can usually be fixed by repressurising, and F.28 or F.29 often comes down to the gas supply or a frozen condensate pipe.
| Code | What it means | Models | Can you fix it? |
|---|---|---|---|
| F.22 | Low water pressure in the boiler (F9 on older models). | Energy range, Betacom A range | Usually yes |
| F.28 | Ignition unsuccessful when starting up (F1 on older models). | Energy range, Betacom A range | Checks first |
| F.29 | Flame loss during operation. | Energy range, Betacom A range | Checks first |
| F.75 | Pressure sensor fault. | Energy range | No, engineer only |
| F.23 | Temperature difference too great between flow and return. | Energy range, Betacom A range | No, engineer only |
| F.72 | Deviation between the water pressure sensor and return temperature sensor. | Energy range, Betacom A range | No, engineer only |
| F.20 | Safety switch-off: overheating temperature reached. | Energy range, Betacom A range | No, engineer only |
| F.25 | Safety switch-off: flue gas temperature too high. | Energy range | No, engineer only |
| F.27 | Safety switch-off: fault in flame detection. | Energy range, Betacom A range | No, engineer only |
| F.61 | Gas valve control system fault. | Energy range, Betacom A range | No, engineer only |
| con | No communication between the PCB and the user interface. | Energy range | No, engineer only |
| Err | User interface fault. | Betacom A range | No, engineer only |
| F.00 | Varies by model: flow temperature sensor fault (Energy range); flow heating temperature sensor fault (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.01 | Varies by model: return temperature sensor fault (Energy range); return heating temperature sensor fault (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.10 | Varies by model: short circuit: flow temperature sensor (Energy range); flow heating temperature sensor fault (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.11 | Varies by model: short circuit: return temperature sensor (Energy range); return heating temperature sensor fault (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.12 | Short circuit: cylinder temperature sensor. | Energy range | No, engineer only |
| F.13 | Short circuit: domestic hot water cylinder temperature sensor. | Energy range | No, engineer only |
| F.24 | Varies by model: safety switch-off: temperature rise too fast (Energy range); water circulation fault (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.26 | Fault in gas valve. | Betacom A range | No, engineer only |
| F.32 | Varies by model: fan speed outside tolerance (fan frost protection active) (Energy range); incorrect air pressure (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.33 | Air pressure switch fault (fan frost protection active). | Energy range | No, engineer only |
| F.49 | eBUS voltage fault. | Betacom A range | No, engineer only |
| F.62 | Fault in the main board. | Betacom A range | No, engineer only |
| F.63 | Fault in the main board. | Betacom A range | No, engineer only |
| F.64 | Varies by model: electronics, sensor or analogue-to-digital converter fault (Energy range); fault in the main board (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.65 | Fault in the main board. | Betacom A range | No, engineer only |
| F.67 | Varies by model: flame signal value from the electronics is incorrect (Energy range); fault in the main board (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.68 | Fluctuation of flame signal. | Betacom A range | No, engineer only |
| F.70 | Varies by model: invalid product code (dsn) (Energy range); user interface incompatible with the main board (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.71 | Varies by model: flow/return temperature sensor fault (Energy range); flow heating temperature sensor fault (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.73 | Varies by model: water pressure sensor not connected or short-circuited (Energy range); heating circuit pressure sensor fault (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.74 | Varies by model: electrical problem in the water pressure sensor (Energy range); heating circuit pressure sensor fault (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.76 | Thermal fuse fault. | Betacom A range | No, engineer only |
| F.77 | Varies by model: condensate or flue fault (Energy range); fault in gas valve motor (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.83 | No water in the installation. | Betacom A range | Usually yes |
| F.84 | Varies by model: flow/return temperature sensor fault (Energy range); permanent temperature difference between flow and return heating sensors (Betacom A range). | Energy range, Betacom A range | No, engineer only |
| F.85 | Flow and return heating sensor fault. | Betacom A range | No, engineer only |
| F.86 | Underfloor heating contact fault. | Betacom A range | No, engineer only |
| F.87 | Electrodes fault. | Energy range | No, engineer only |
| F.89 | Pump fault. | Energy range | No, engineer only |