BoilerFaultCodesTechnical description
Frostprotectionmode(Comfort):Minimumload
What causes this fault?
This occurs when the boiler's internal sensors detect that the water temperature has dropped to a level where there is a risk of freezing. To protect itself, the boiler automatically fires up at a minimum heat level to circulate warm water through the internal components. This is a normal safety function designed to prevent the heat exchanger from cracking due to ice expansion.
This status is almost exclusively seen during the winter months or during sudden overnight cold snaps when temperatures drop near freezing.
DIY fix possible
Check that your external condensate pipe is not frozenEnsure radiators are turned on and TRVs are open to allow water circulationWait for the boiler to finish the frost protection cycle; it will return to normal once the temperature rises