BoilerFaultCodesWhat the manual says
Manufacturer manualAnti frost mode active
What causes this fault?
This status occurs when the internal sensors detect that the water temperature inside the boiler has dropped below a safe threshold, usually around 5°C. To protect itself from damage, the boiler automatically fires up to circulate warm water and prevent the heat exchanger from freezing solid. It is a safety feature rather than a mechanical failure.
This code is almost exclusively seen during the winter months when outdoor temperatures drop near or below freezing.
DIY fix possible
Wait for the boiler to finish its cycle; the status will clear once the internal temperature rises.Ensure your thermostat is turned up to your desired temperature.Check that any external pipes, such as the condensate pipe, are not frozen solid.
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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