BoilerFaultCodesTechnical description
Anti-frost mode is active
What causes this fault?
The boiler's internal temperature sensors have detected that the water inside the unit has dropped below a safe threshold, typically around 5°C. To protect itself from damage caused by ice expansion, the boiler automatically fires up to circulate warm water until it reaches a safer temperature. This is a built-in safety feature rather than a mechanical failure.
This status code is most common during the winter months or during overnight cold snaps when external temperatures drop significantly.
DIY fix possible
Check that your external condensate pipe is not frozenEnsure your thermostat is set to your desired temperatureWait for the boiler to finish its warming cycle and return to normal operation
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