BoilerFaultCodesWhat the manual says
Manufacturer manualHeating mode: Frost protection. The frost protection function for heating mode is activated.
What causes this fault?
This occurs when the internal temperature sensor drops below 5°C, triggering the boiler to automatically fire up and run the pump. It is a built-in safety feature designed to circulate warm water and prevent the heat exchanger from cracking due to ice expansion. The boiler will stop this mode once the internal temperature reaches a safe level, usually around 30°C.
This status is most common during extreme winter cold spells, particularly if the boiler is located in a cold garage, loft, or outbuilding.
DIY fix possible
Check that your external condensate pipe is not frozen or blocked with iceEnsure your main gas and electrical supply to the boiler remains switched onWait for the boiler to finish its cycle; the code should disappear once the temperature rises
Avoid the next call-out bill
A cover plan would handle faults like S.34: no call-out fees, no surprise bills.
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