BoilerFaultCodesGlow-worm S.30 Fault Code
Also written as S30 — same fault.
The Glow-worm S.30 fault code means: your boiler is working fine but hasn't started the heating because your external thermostat or timer is currently telling it to stay off.. It appears on 29 Glow-worm models in our database.
Technical description: No Heating demand from external controls 230V
What causes the Glow-worm S.30 fault?
This status code occurs because the boiler's internal computer is waiting for a signal from your wall thermostat or timer before it begins heating your radiators. The most common reason is simply that the room temperature is already higher than the setting on your thermostat, or your heating schedule is currently set to an 'off' period. It can also be caused by flat batteries in a wireless thermostat preventing the 'switch on' signal from reaching the boiler.
This code is frequently seen during the transition into autumn, when homeowners first try to turn their heating on only to find their thermostat batteries have died over the summer.
DIY fix possible
Check that your room thermostat is turned up higher than the current room temperature.Ensure your programmer or central heating timer is set to 'On' or 'Auto'.Replace the batteries in your wireless wall thermostat if the screen is blank or showing a low battery symbol.
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Glow-worm models that show the S.30 fault code
Click a model for the full fault code list and model-specific repair notes.
- 30cxi
- 38cxi
- Betacom4 Repair: £80-150
- Easicom 24
- Easicom3 Combi
- Easicom3 System
- Energy
- Energy Regular
- Energy System
- Energy7 Combi
- Energy7 Regular
- Energy7 System
- Essential
- Flexicom 18sx Repair: £0-120
- Flexicom 24c / 28c
- Flexicom cx Repair: £0-120
- Flexicom hx Repair: £0-120
- Flexicom sx Repair: £0-120
- Sustain 12s
- Ultimate 3 25R
- Ultimate3 Combi
- Ultimate3 System
- Ultracom 2 CXI Repair: £0-120
- Ultracom 2 HXI Repair: £0-120
- Ultracom 2 SXI Repair: £0-120
- Ultracom 24cx 30cx Repair: £0-120
- Ultracom 35 Store Repair: £0-120
- Ultracom cxi Repair: £0-120
- Ultracom sxi Repair: £0-120
Source
Glow-worm S.30 fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026