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Glowworm
Fault Codes
Listed below are the common Glowworm fault codes as described by the boiler manufacturer along with a possible cause.
Glow-worm Boiler Error Codes
| Boiler Model | Fault Code | Cause of Problem |
|---|---|---|
| Betacom | Red LED on | Lockout – low water pressure (increase pressure to 1.5bar) and reset boiler |
| Betacom | Red LED flashing | Overheat – check both overheat stats |
| Betacom | Yellow LED flashing | Turn domestic hot water (DHW) control knob into temperature range and turn central heating (CH) temperature control knob into power (reset position) and wait for minimum of 30 seconds before turning into either summer or temperature position |
| Betacom | Yellow LED on | Flame present on the burner |
| Betacom | Green LED on | Boiler ready for operation |
| Betacom | Green LED off | No power to boiler – Check for 230volts into the appliance, check fuse on printed circuit board (PCB) |
| Betacom / Ultracom₂ cxi / sxi / 35 | F00 / F10 / F71 | Flow heating temperature sensor fault |
| Betacom / Ultracom₂ cxi / sxi / 35 | F01 / F11 | Return heating temperature sensor fault |
| Betacom / Ultracom₂ cxi / sxi / 35 | F20 | Overheating fault |
| Betacom / Ultracom₂ cxi / sxi / hxi / 35 / Flexicom cx / hx / sx | F9 / F22 | Low water pressure (or ignition temperature rise too slow) |
| Betacom / Ultracom₂ cxi / sxi / 35 | F26 / F77 | Fault in gas valve |
| Betacom / Ultracom₂ cxi / sxi / 35 / CI / hxi / Xtramax HE | F27 / F16 | Flame detection fault |
| All Boilers | F28 / F1 / F4 | Ignition fault (flame detection) |
| Betacom / Ultracom₂ cxi / sxi / 35 | F29 | Loss of flame during operation |
| Betacom / Ultracom₂ cxi / sxi / 35 | F32 | Incorrect air pressure |
| Betacom / Ultracom₂ cxi / sxi / 35 | F49 | EBUS voltage fault |
| Betacom / Ultracom₂ cxi / sxi / 35 | F61 / F62 / F63 / F64 / F65 / F67 | Fault in the main board |
| Betacom / Ultracom₂ cxi / sxi / 35 | F68 | Fluctuation of flame signal |
| Betacom / Ultracom₂ cxi / sxi / 35 | F70 | User interface incompatible with the main board |
| Betacom / Ultracom₂ cxi / sxi / 35 | F72 / F84 | Permanent temperature difference between flow and return heating sensors |
| Betacom / Ultracom₂ cxi / sxi / 35 | F73 / F74 | Heating circuit pressure sensor fault |
| Betacom / Ultracom₂ cxi / sxi / 35 | F76 | Thermal fuse fault |
| Betacom / Ultracom₂ cxi / sxi / 35 | F83 | Thermal fuse fault |
| Betacom / Ultracom₂ cxi / sxi / 35 | F85 | Flow and Return heating sensor fault |
| Betacom / Ultracom₂ cxi / sxi / 35 | F86 | Underfloor heating contact fault |
| All Boilers | ERR / F12 / F18 | User interface fault |
| Betacom c | Temperature 30 flashing | Fault on central heating (CH) thermistor |
| Betacom c | Temperature 40 flashing | Fault on DHW thermistor |
| Betacom c | Temperature 50 flashing | Fault on outside sensor |
| Betacom c | Temperature 60 flashing | Low system pressure |
| Betacom c | Temperature 70 flashing | Fault on APS |
| Betacom c | Temperature 80 flashing | Overheat open circuit |
| Betacom c | Temperature 90 flashing | Flame or gas failure |
| Compact e / s | No DHW | Check dhw microswitch / Check external controls, Please test for 230V on switch live contact |
| Compact e / s | No C/H | Check dhw microswitch if dhw demand led is lit / Check external controls, Please test for 230V on switch live contact |
| Compact e / s | No C/H but boiler is firing | Check divertor motor and cartridge / Check external controls, Please test for 230V on switch live contact |
| Compact e / s | Boiler locks out within 10 seconds | Check pump proving switch, air pressure switch and overheat state / Check pump proving switch, air pressure switch and overheat stat |
| Compact e / s | Poor burner pressure | Check burner pressure/ignition adjustment pots on PCB |
| Ci Range (plus) / Si range | F2 | Fan/APS |
| All Boilers | F5 | Overheat Fault |
| All Boilers | F6 | Central heating flow thermistor |
| All Boilers | F7 | Domestic hot water thermistor |
| All Boilers | F8 | Tank thermistor fault |
| sxi / si / ci (plus) range / Xtramax HE | F9 | Water pressure sensor fault (please contact GW technical department for further information) |
| All boilers | F10 | Central return flow thermistor |
| All boilers | F11 | Main board connection fault |
| Ci (plus) / cxi / hxi / si / sxi range | F12 | Connection fault between main printed circtuit board (PCB) and display PCB |
| Ci (plus) / cxi / hxi / si / sxi range | F13 | Main pcb connection fault |
| Ci (plus) / cxi / hxi / si / sxi range | F14 | Central heating flow temperature > 95 degrees |
| Ci (plus) / cxi / si / sxi range | F15 | Gas valve stepper motor fault |
| Ci (plus) / cxi / hxi / si / sxi range / Xtramax HE | F17 | Power supply is less than 170v |
| Ci (plus) / cxi / hxi / si / sxi range / Xtramax HE | F19 | Central heating thermistor unplugged |
| Ci (plus) / cxi / hxi / si / sxi range / Xtramax HE | F20 | Software incompatibility |
| cxi / hxi / sxi range / Flexicom cx | F24 | Central heating return temperature > 90 degrees |
| cxi / hxi / sxi / Xtrafast 96/120 / Xtrafast 96/120E1 | F25 / F26 / F11 | Poor circulation |
| ci range | F3 | Air fault |
| ci range | F3 | Air fault |
| cxi / sxi / hxi range/ Xtramax HE | F2 / F3 | Fan |
| cxi / sxi range / Flexicom cx / hx / sx / hxi / Ultracom cxi / cx / hxi / sxi / Ultrapower sxi | F3 | Fan unable to reach ignition speed |
| Flexicom cx / hx / sx / hxi / Ultracom cxi / cx / hxi / sxi | F9 | Water pressure sensor fault, blocked flow filter or pump fault |
| Flexicom cx / hx / sx | F11 | Flow and or return thermistor fault |
| Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HE | F13 | PCB memory or sensing fault |
| Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HE | F14 | Gas valve control defective |
| Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HE | F15 | E-bus voltage failure |
| All boilers | F25 / F23 | Circulation fault |
| Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi | F43 | Generic error |
| Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi | F70 | Software incompatible |
| Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi | F73 | Unable to see pump activate |
| Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi | F77 | Condensate pump error (optional) |
| hxi range | F9 | Earlier models only (please contact GW technical department for further information) |
| hxi range | F9 | Earlier models only (please contact GW technical department for further information) |
| Ultracom₂ 35 Store | F02 / F12 | Hot water temperature sensor fault |
| Ultracom₂ 35 Store | F03 / F13 / F79 | Storage tank temperature sensor fault |
| Ultracom₂ 35 Store | F81 | Overheating of hot water circuit |
| All Ultracom | No display or Er | loose connection X51 |
| Xtramax HE Range | F24 | Cental heating return temperature > 90 degrees |
| Xtramax HE Range | F25 | Maximum temperature rise slope |
| Xtramax HE Range | F26 | Maximum delta temperature |
| Xtrafast 96/120 Range | F00 | No fault/td> |
| Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | F00 | No fault |
| Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | F02 | Air flow fault |
| Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | F05 | Overheating |
| Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | F06 | Central heating thermistor/wiring fault |
| Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | F08 | Storage vessel thermistor/wiring fault |
| Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | F09 | System pressure sensor fault |
| Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | F10 | Fan fault |
| Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | F13 | Main printed circuit board (PCB) fault |
| Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | F14 | Central heating flow temperature > 97 degrees |
| Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | F15 | Gas mechanism fault |
| Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | F20 | Communication fault |
Glow-worm Energy Boiler Range Error Codes
| Fault Code | Cause of Problem |
|---|---|
| F.00 | Flow temperature sensor |
| F.00 | Flow temperature sensor |
| F.10 | Flow temperature sensor short circuit |
| F.11 | Flow temperature sensor short circuit |
| F.12 and F.91 | Cylinder temperature sensor short circuit |
| F.13 | Domestic hot water cylinder temperature sensor short circuit |
| F.20 | Safety switch-off – overheating temperature reached |
| F.22 | Safety switch-off – low water pressure in boiler |
| F.23 | Safety switch-off – temperature difference too great (NTC1/NTC2) |
| F.24 | Safety switch-off – temperature rise too fast |
| F.25 | Safety switch-off – flue gas temperature too high |
| F.27 | Safety switch-off – fault in flame detection |
| F.28 | Ignition unsuccessful when starting up |
| F.29 | Flame loss |
| F.32 | Fan frost protection function active – fan speed outside the tolerance values |
| F.33 | Fan frost protection function active – air pressure switch fault |
| FA9 | eBUS fault – voltage too low |
| F.61 | Gas valve control system fault |
| F.82 | Gas valve switch-off control fault |
| F.83 | EEPROM fault – electronics defective |
| F.64 | Electronics/sensor/analogue-to-digital converter fault |
| F.85 | Electronics temperature too high |
| F.67 | Value sent back by ASIC is incorrect (flame slgnal) |
| F.88 | Unstable flame (analogue input), underfloor heating contact or gas valve fault |
| F.70 | Invalid product code (DSN) |
| F.71 | Flow/return temperature sensor |
| F.72 | Deviation in the water pressure sensor/return temperature sensor |
| F.73 | Water pressure sensor not connected or has short-circuited |
| F.74 | Electrical problem in the water pressure sensor |
| F.75 | Pressure sensor fault |
| F.78 | The safety cut-out in the primary heat exchanger is defective |
| F.77 | Fault: Condensate or smoke |
| F.78 | Interruption to domestic hot water (DHW) outlet sensor at external controller |
| F.83 | Burner temperature sensor fault |
| F.84 | Flow/return temperature sensor fault |
| F.85 | Temperature sensor fault |
| F.87 | Electrodes fault |
| F.89 | Pump fault |
| Connection | No communication between the printed circuit board (PCB) and the user interface |
Glow-worm Error Codes F1, F4, F28 or F29
If you are seeing the error codes F1, F4 F28 or F29 on your boiler there’s an issue with your condensate pipe. This error appears when your pipe is frozen, which can happen during the cold months as it runs outdoors. You can fix this issue yourself if you feel confident enough, otherwise call an engineer.
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