Low
S.30 on Vaillant Home System

Your boiler is working fine, but your wall thermostat or heating controls have told it to stay switched off.

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

Room thermostat is blocking heating mode.

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

Check if your room thermostat is set higher than the current room temperature.Replace the batteries in your wireless wall thermostat or programmer.Ensure your heating timer or app is set to an 'On' period.

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Related fault codes

S.31View →S.0View →

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