Low
S.30 on Vaillant ecoFIT Pure 435

Your boiler is perfectly healthy, but it is currently waiting for a signal from your thermostat to tell it that your home needs more heat.

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 Ecofit Pure 830 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

Locate your room thermostat or smart controllerTurn the target temperature up higher than the current room temperatureCheck if the boiler begins its ignition process once the thermostat displays an active heating symbol

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