Low
S.34 on Vaillant Home System

Your boiler has sensed that the temperature inside is too low and has automatically turned itself on to prevent the water from freezing and damaging the pipes.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Frost protection active

From this model's manual
Verified against the Vaillant Home System installation & service manual, page 33.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Ensure the boiler power remains switched onCheck that your external condensate pipe is not frozenEnsure any radiator valves in the room are open to allow water to circulateWait for the boiler to finish the frost protection cycle and return to normal operation

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