BURNER FIRING 100% Low

Grant BURNER FIRING 100% Fault Code

Also written as BURNERFIRING100 — same fault.

The Grant BURNER FIRING 100% fault code means: your boiler is currently operating at its highest power setting to meet a high demand for heat or hot water, and this is a normal status message rather than a fault.. It appears on 1 Grant 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: Burner display showing maximum output status

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

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Grant models that show the BURNER FIRING 100% fault code

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

Source

Grant BURNER FIRING 100% fault code information on this page is sourced and cross-checked against the official Grant service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026