Low
S.109 on Vaillant Home System

Your boiler is currently taking a break because it has finished heating your home and is waiting for the next request for warmth.

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

Product's standby mode activated

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 that your room thermostat is set high enough to call for heatEnsure your programmer or timer is set to an 'On' periodWait 10-15 minutes, as the boiler may simply be in a natural pause between heating cycles

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