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  • Glow-Worm Boiler Error Codes / Fault Codes

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    • Glow-Worm Boiler Error Codes / Fault Codes

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  • Glow-Worm Boiler Error Codes / Fault Codes

    • home
    • Blog
    • Glow-Worm Boiler Error Codes / Fault Codes

    Updated: March 21, 2024

    When it comes to home heating systems, boilers play a crucial role in keeping our homes warm and comfortable. Among the many reputable boiler brands available, Glow-Worm has gained recognition for its reliable and efficient heating solutions. However, like any complex machinery, Glow-Worm boilers can sometimes encounter issues that may disrupt their operation and require troubleshooting.

    When it comes to home heating systems, boilers play a crucial role in keeping our homes warm and comfortable. Among the many reputable boiler brands available, Glow-Worm has gained recognition for its reliable and efficient heating solutions. However, like any complex machinery, Glow-Worm boilers can sometimes encounter issues that may disrupt their operation and require troubleshooting.

    What are boiler fault codes?

    Boiler fault codes are alphanumeric codes that indicate specific issues or faults in a boiler system. These codes are generated by the boiler’s control panel or electronic control unit (ECU) to help diagnose problems and facilitate troubleshooting.

    Glow-worm is a British boiler company which has a heating experience of more than 75 years. Glow-worm aim has always been to provide products which are top quality and reliable.

    That being said, boilers of top quality do sometimes tend to have certain issues. On this page you will find the error codes or faults of Glow-worm boilers and what they indicate, in addition to possible ways to fix these issues.

    A short history of Glow-worm

    Glow-worm started producing boilers back in 1934 at the Derwent Foundry in Derbyshire. In 2001, Glow-worm became part of the Vaillant Group. It is worth mentioning that Vaillant is the second-largest heating company in Europe.

    Glow-worm manufacturing different gas boilers that include different sizes and types such as combi, system or regular heat-only boilers.

    They also state that “it has been the drive which has led us right to the top as one of the leading heating manufacturers in the UK”.

    Vaillant has a staff of 12,000 workers across Europe and China. They offer innovative heating, ventilation, air-conditioning technology to countless homes all over the world.

    Read more: Common Sime Boiler Error Codes

    Main Boiler Error Codes / Fault Codes

    Glow-worm Boiler Error Codes

    Model of BoilerFault Codes Cause of the Issue
    BetacomRed LED OnLockout – low water pressure (increase pressure to 1.5bar) and reset boiler
    BetacomRed LED flashingOverheat – check both overheat stats
    BetacomYellow LED flashingTurn domestic hot water (DHW) control knob into temperature range and turn central heating (CH) temperature control knob into power (reset position) 
    BetacomYellow LED onFlame present on the burner
    BetacomGreen LED onGreen LED on
    BetacomGreen LED offNo power to boiler – Check for 230volts into the appliance, check the fuse on printed circuit board (PCB)
    Betacom4 / Ultracom3 cxi / sxi / 35F00 / F10 / F71Flow heating temperature sensor fault
    Betacom4 / Ultracom3 cxi / sxi / 35F01 / F11Return heating temperature sensor fault
    Betacom4 / Ultracom3 cxi / sxi / 35F20Overheating fault
    Betacom4 / Ultracom3 cxi / sxi / hxi / 35 / Flexicom cx / hx / sxF9 / F22Low water pressure (or ignition temperature rise too slow)
    Betacom4 / Ultracom3 cxi / sxi / 35F26 / F77Fault in gas valve
    Betacom4 / Ultracom3 cxi / sxi / 35 / CI / hxi / Xtramax HEF27 / F16Flame detection fault
    All BoilersF28 / F1 / F4Ignition fault (flame detection)
    Betacom4 / Ultracom3 cxi / sxi / 35F29Loss of flame during operation
    Betacom4 / Ultracom3 cxi / sxi / 35F32Incorrect air pressure
    Betacom4 / Ultracom3 cxi / sxi / 35F49EBUS voltage fault
    Betacom4 / Ultracom3 cxi / sxi / 35F61 / F62 / F63 / F64 / F65 / F67Fault in the main board
    Betacom4 / Ultracom3 cxi / sxi / 35F68Fluctuation of flame signal
    Betacom4 / Ultracom3 cxi / sxi / 35F70User interface incompatible with the main board
    Betacom4 / Ultracom3 cxi / sxi / 35F72 / F84Permanent temperature difference between flow and return heating sensors
    Betacom4 / Ultracom3 cxi / sxi / 35F73 / F74Heating circuit pressure sensor fault
    Betacom4 / Ultracom3 cxi / sxi / 35F76Thermal fuse fault
    Betacom4 / Ultracom3 cxi / sxi / 35F83Thermal fuse fault
    Betacom4 / Ultracom3 cxi / sxi / 35F85Flow and Return heating sensor fault
    Betacom4/ Ultracom3 cxi / sxi / 35F86Underfloor heating contact fault
    All BoilersERR / F12 / F18User interface fault
    Betacom cTemperature 30 flashingFault on central heating (CH) thermistor
    Betacom cTemperature 40 flashingFault on DHW thermistor
    Betacom cTemperature 50 flashingFault on outside sensor
    Betacom cTemperature 60 flashingLow system pressure
    Betacom cTemperature 70 flashingFault on APS
    Betacom cTemperature 80 flashingOverheat open circuit
    Betacom cTemperature 90 flashingFlame or gas failure
    Compact e / sNo DHWCheck dhw microswitch / Check external controls, Please test for 230V on switch live contact
    Compact e / sNo C/HCheck dhw microswitch if dhw demand led is lit / Check external controls, Please test for 230V on switch live contact
    Compact e / sNo C/H but boiler is firingCheck divertor motor and cartridge / Check external controls, Please test for 230V on switch live contact
    Compact e / sBoiler locks out within 10 secondsCheck pump proving switch, air pressure switch and overheat state / Check pump proving switch, air pressure switch and overheat stat
    Compact e / sPoor burner pressureCheck burner pressure/ignition adjustment pots on PCB
    Ci Range (plus) / Si rangeF2Fan/APS
    All BoilersF5Overheat Fault
    All BoilersF6Central heating flow thermistor
    All BoilersF7Domestic hot water thermistor
    All BoilersF8Tank thermistor fault
    sxi / si / ci (plus) range / Xtramax HEF9Water pressure sensor fault (please contact GW technical department for further information)
    All boilersF10Central return flow thermistor
    All boilersF11Main board connection fault
    Ci (plus) / cxi / hxi / si / sxi rangeF12Connection fault between main printed circuit board (PCB) and display PCB
    Ci (plus) / cxi / hxi / si / sxi rangeF13Main pcb connection fault
    Ci (plus) / cxi / hxi / si / sxi rangeF14Central heating flow temperature > 95 degrees
    Ci (plus) / cxi / si / sxi rangeF15Gas valve stepper motor fault
    Ci (plus) / cxi / hxi / si / sxi range / Xtramax HEF17Power supply is less than 170v
    Ci (plus) / cxi / hxi / si / sxi range / Xtramax HEF19Central heating thermistor unplugged
    Ci (plus) / cxi / hxi / si / sxi range / Xtramax HEF20Software incompatibility
    cxi / hxi / sxi range / Flexicom cxF24Central heating return temperature > 90 degrees
    cxi / hxi / sxi / Xtrafast 96/120 / Xtrafast 96/120E1F25 / F26 / F11Poor circulation
    ci rangeF3Air fault
    cxi / sxi / hxi range/ Xtramax HEF2 / F3Fan
    cxi / sxi range / Flexicom cx / hx / sx / hxi / Ultracom cxi / cx / hxi / sxi / Ultrapower sxiF3Fan unable to reach ignition speed
    Flexicom cx / hx / sx / hxi / Ultracom cxi / cx / hxi / sxiF9Water pressure sensor fault, blocked flow filter or pump fault
    Flexicom cx / hx / sxF11Flow and or return thermistor fault
    Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HEF13PCB memory or sensing fault
    Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HEF14Gas valve control defective
    Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HEF15E-bus voltage failure
    All boilersF25 / F23Circulation fault
    Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxiF43Generic error
    Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxiF70Software incompatible
    Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxiF73Unable to see pump activate
    Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxiF77Condensate pump error (optional)
    hxi rangeF9Earlier models only (please contact GW technical department for further information)
    Ultracom? 35 StoreF02 / F12Hot water temperature sensor fault
    Ultracom? 35 StoreF03 / F13 / F79Storage tank temperature sensor fault
    Ultracom? 35 StoreF81Overheating of hot water circuit
    All UltracomNo display or Erloose connection X51
    Xtramax HE RangeF24Cental heating return temperature > 90 degrees
    Xtramax HE RangeF25Maximum temperature rise slope
    Xtramax HE RangeF26Maximum delta temperature
    Xtrafast 96/120 RangeF00No-fault
    Xtrafast 96/120 Range / Xtrafast 96/120E1 RangeF00No-fault
    Xtrafast 96/120 Range / Xtrafast 96/120E1 RangeF02Airflow fault
    Xtrafast 96/120 Range / Xtrafast 96/120E1 RangeF05Overheating
    Xtrafast 96/120 Range / Xtrafast 96/120E1 RangeF06Central heating thermistor/wiring fault
    Xtrafast 96/120 Range / Xtrafast 96/120E1 RangeF08Storage vessel thermistor/wiring fault
    Xtrafast 96/120 Range / Xtrafast 96/120E1 RangeF09System pressure sensor fault
    Xtrafast 96/120 Range / Xtrafast 96/120E1 RangeF10Fan fault
    Xtrafast 96/120 Range / Xtrafast 96/120E1 RangeF13Main printed circuit board (PCB) fault
    Xtrafast 96/120 Range / Xtrafast 96/120E1 RangeF14Central heating flow temperature > 97 degrees
    Xtrafast 96/120 Range / Xtrafast 96/120E1 RangeF15Gas mechanism fault
    Xtrafast 96/120 Range / Xtrafast 96/120E1 RangeF20Communication fault

    Read about: Ferroli Boiler Error Codes / Fault codes List

    Biasi Boiler Error Codes / Fault Codes 

    Glow-worm Energy boiler range error codes

    Fault CodeCause of the Issue
    F.00Flow temperature sensor
    F.10Flow temperature sensor short circuit
    F.12 and F.91Cylinder temperature sensor short circuit
    F.13Domestic hot water cylinder temperature sensor short circuit
    F.20Safety switch-off – overheating temperature reached
    F.22Safety switch-off – low water pressure in the boiler
    F.23Safety switch-off – temperature difference too great (NTC1/NTC2)
    F.24Safety switch-off – temperature rise too fast
    F.25Safety switch-off – flue gas temperature too high
    F.27Safety switch-off – fault in flame detection
    F.28Ignition unsuccessful when starting up
    F.29Flame loss
    F.32Fan frost protection function active – fan speed outside the tolerance values
    F.33Fan frost protection function active – air pressure switch fault
    FA9eBUS fault – voltage too low
    F.61Gas valve control system fault
    F.82Gas valve switch-off control fault
    F.83EEPROM fault – electronics defective
    F.64Electronics/sensor/analogue-to-digital converter fault
    F.85Electronics temperature too high
    F.67Value sent back by ASIC is incorrect (flame signal)
    F.88Unstable flame (analogue input), underfloor heating contact or gas valve fault
    F.70Invalid product code (DSN)
    F.71Flow/return temperature sensor
    F.72Deviation in the water pressure sensor/return temperature sensor
    F.73Water pressure sensor not connected or has short-circuited
    F.74Electrical problem in the water pressure sensor
    F.75Pressure sensor fault
    F.78The safety cut-out in the primary heat exchanger is defective
    F.77Fault: Condensate or smoke
    F.78Interruption to domestic hot water (DHW) outlet sensor at external controller
    F.83Burner temperature sensor fault
    F.84Flow/return temperature sensor fault
    F.85Temperature sensor fault
    F.87Electrodes fault
    F.89Pump fault
    ConnectionNo communication between the printed circuit board (PCB) and the user interface

    Read more: Biasi Boiler Error Codes / Fault Codes 

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    FAQs

    How long will a Glow Worm boiler last?

    A good quality boiler is expected to last around 10 to 15 years.

    Are Glow Worm and Vaillant the same company?

    In 2001 Glow-worm was acquired by the Vaillant Group.

    How efficient are Glow Worm boilers?

    In terms of energy efficiency, all of the Glow Worm regular boilers are B-rated, varying between 89.3 – 89.7% (nearly A-rated) with the exception of the Easicom 3, which is 94% energy efficient.

    Are Glow-worm boilers condensing?

    Yes. Glow-worm is a trusted manufacturer of high-efficiency combi and condensing boilers.