Low
B Illuminated continuously on Alpha CB24

Your boiler is operating exactly as it should be, and the 'B' light simply confirms that the burner is currently lit and heating your water.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

Indicates the burner is alight.

From this model's manual
Verified against the Alpha Alpha Cb24 installation & service manual, page 18.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

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

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