BoilerFaultCodesWhat the manual says
Manufacturer manualFrost protection mode
What causes this fault?
This occurs when the sensors inside your boiler detect that the water temperature has dropped near freezing levels, usually below 5°C. The boiler automatically fires up to circulate warm water and prevent the heat exchanger from cracking due to ice expansion. It is a normal safety function rather than a mechanical failure.
This status code is most common during extreme winter cold spells, particularly if the boiler is located in an unheated area like a garage or loft.
DIY fix possible
Wait for the boiler to finish its defrost cycle automaticallyEnsure the room thermostat is turned up to a normal heating temperatureCheck that any external condensate pipes are not frozen or blocked
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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