8.79 Low

Glow-worm 8.79 Fault Code

Also written as 879 — same fault.

The Glow-worm 8.79 fault code means: this code is not actually an error, but a technical display showing the boiler's current power output level while it is operating normally.. It appears on 1 Glow-worm model in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: NOMINAL kW HEAT OUTPUT

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Glow-worm models that show the 8.79 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Glow-worm 8.79 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