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Glow-worm fault codes
Checked against its sources: Updated
Glow-worm fault codes defined in the user manuals read are mainly F.22, F.28 and F.83, with F1, F5 and F22 on the older Flexicom cx. A longer list exists only on Glow-worm's website, and the rows below say which is which.127 The user manuals read don't list other numbers.
- Covers
- Glow-worm boilers named below, gas; website rows name no model
- You
- Fill by the method your installer showed, reset by your model's method, and read the display. Only what your own manual allows.
- A professional
- Everything else. Glow-worm's website says not to get inside the boiler.
1 Codes in the user manuals
| Code or display | What the Glow-worm manual says | Which manual, page | What the Glow-worm manual lets you do |
|---|---|---|---|
| F.22 | Water deficiency or low water pressure | Energy7 (02.03.2020) p141; Ultimate 3 (15.07.2019) p152; Betacom 4 (05.08.2019) p153; Energy 2 LPG p144 | Fill the installation. Ultimate 3, Betacom 4: competent person if pressure drops often |
| F.28 | Ignition failed; fault mode after three failed attempts | Energy7 p141; Ultimate 3 p162; Betacom 4 p163; Energy 2 p144 | Reset; competent person after three attempts |
| F.83 | No cause given: press reset; if it persists after one more press, a 45-minute anti-cycling time starts | Energy7 p151; Energy 2 p154 | As printed; competent person if it persists |
| S.54 | Shown during that 45-minute time | Energy7 p151; Energy 2 p154 | Wait |
| F1 (Flexicom cx) | Boiler attempted to light five times and failed | Flexicom cx (06/11) p136 | Press reset; installer or Glow-worm if it persists |
| F5 (Flexicom cx) | Overheat | Flexicom cx p136 | Allow to cool, then press reset |
| F22 (Flexicom cx) | Low water pressure, or ignition temperature rise too slow | Flexicom cx p136 | Fill with the loop until 1.0 bar shows, close the taps, remove the loop; installer if it persists |
| Reset-style display (picture) | Fault | Ultracom 2 cxi (03/10) PDF p155 | Press reset, wait 5 seconds; installer or Glow-worm if it persists |
| F0xx (picture) | Fault | Ultracom 2 cxi PDF p155 | Contact installer or Glow-worm |
| Flashing pressure, such as 0.4 | Lack of water, below 0.5 bar | Ultracom 2 cxi PDF p155 | Fill to 0.8 to 1.2 bar |
| High pressure reading (picture) | Excess water | Ultracom 2 cxi PDF p155 | With the heating off and the radiator cool, bleed it, or call |
2 Codes only on Glow-worm's website
The page names no model. These rows are not in any user manual read, so your boiler's own manual still decides.7
| Code | What the page says | Source | The page's advice |
|---|---|---|---|
| F.0, F.1 | Flow sensor; return sensor interrupted | Maker's website only | Glow-worm engineer |
| F.10, F.11 | Flow sensor; return sensor short-circuit | Maker's website only | Glow-worm engineer |
| F.20 | Safety thermal cut-out operated | Maker's website only | Check pressure, leaks, radiator valves; installer first |
| F.22 | Low pressure | Maker's website, matches manuals | Under 1 bar a competent user may top up to 1 to 1.5 bar "at your own risk"; over 1 bar, engineer |
| F.23 | Flow and return difference too great | Maker's website only | Installer |
| F.24 | Temperature rising too quickly | Maker's website only | Installer or engineer, by boiler type |
| F.27 | Flame detected with burner off | Maker's website only | Expert |
| F.28, F.29 | Failed to ignite; flame out, failed to reignite | F.28 also in manuals; F.29 website only | Check other gas appliances, prepayment credit, outdoor condensate pipe for ice; then engineer |
| F.32 | Fan fault | Maker's website only | Engineer |
| F.70 | Device number incorrect or missing | Maker's website only | Engineer |
| F.72, F.84 | Flow and return spread invalid; implausible differences | Maker's website only | Installer |
| F.75 | Pressure change too low at pump start | Maker's website only | Under 1 bar, as F.22 |
| F.83 | Little or no temperature rise at burner start | Meaning on website only | Installer |
| F.88 | Gas valve connection interrupted | Maker's website only | Engineer |
3 How the reset works on each family
Energy7: press reset for one second. Energy 2: fault clearance key for one second. Competent person after three attempts on both.14 Ultimate 3 and Betacom 4: press the button pictured; the manual text read gives no duration; three attempts.23 Ultracom 2 cxi: press reset, wait 5 seconds.5 The website says resetting "often" helps but prints no limit, so use the manual and try once.7
4 Where the sources differ
Pressure guidance varies with the model: see what the gauge should read. Energy7 says to have a condensate fault fixed by a competent person, while the older Flexicom cx and Ultracom 2 cxi say warm cloths may release ice.165 See frozen condensate pipe. If you smell gas, use the gas entry.
Sources
- Glow-worm Energy7 25c, 30c, 35c -A operating instructions, 0020300878_00, 02.03.2020, Glow-worm read 3 November 2026.
- Glow-worm Ultimate 3 30c, 35c operating instructions, 0020239565_01, 15.07.2019, Glow-worm read 3 November 2026.
- Glow-worm Betacom 4 24c, 30c -A operating instructions, 0020238423_02, 05.08.2019, Glow-worm read 3 November 2026.
- Glow-worm Energy 2 30c -A LPG operating instructions, 0020283672_00, undated in the copy read, Glow-worm read 3 November 2026.
- Glow-worm Ultracom 2 cxi user manual, 0020085232_01, 03/10, PDF pp15-16 (printed page numbers differ), Glow-worm read 3 November 2026.
- Glow-worm Flexicom cx instructions for use, discontinued range, 0020127401_00, 06/11, pp12-13, Glow-worm read 3 November 2026.
- Boiler fault codes, Glow-worm web page, not a manual read 3 November 2026.