BoilerFaultCodesTechnical description
Frost protection mode
What causes this fault?
This status occurs when the internal temperature sensor within the boiler drops below 5°C. To protect itself from frost damage, the boiler automatically ignites to warm the primary heat exchanger and circulate water until a safe temperature is reached. It is a built-in safety feature rather than a mechanical failure.
This code is almost exclusively seen during winter or periods of extreme cold when the ambient temperature around the boiler drops significantly.
DIY fix possible
Check that your external condensate pipe is not frozenEnsure your boiler is left powered on so the protection can runIncrease the room thermostat slightly to help warm the area around the boiler
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