Low
F1 on Atag A200

Your boiler is notifying you that a specific brand of system protector or anti-freeze chemical has been detected in the water to help prevent internal corrosion and freezing.

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.

Technical description

Anti-freeze in combination with protector (Fernox F1 / Alphi 11)

DIY fix possible

Press the Reset button on the control panelMonitor the display to see if the code clearsIf the code persists, check your system pressure is between 1.0 and 1.5 bar

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