Low
F4 on Alpha Intec 50CS

Your boiler is simply performing a routine safety clear-out to remove any remaining exhaust gases after finishing a heating or hot water cycle.

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

Post ventilation in progress. Fan in function after a request for domestic hot water or central heating in order to evacuate residual fumes.

From this model's manual
Verified against the Alpha Intec 50cs installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Wait for a few minutes to allow the fan to finish its cooling cycleMonitor the display to see if the code clears and the boiler resumes normal standby modeEnsure there are no obstructions to the external flue terminal

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