Low Information
D.8 on Vaillant ecoTEC plus Regular

Your boiler is working correctly and is simply indicating that your external thermostat or programmer is asking it to provide 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.

Technical description

External controls heat demand

What causes this fault?

This status occurs when your external thermostat or wall programmer sends an electrical signal to the boiler asking for heating or hot water. It identifies that the boiler is receiving a command to fire up and is functioning exactly as it should to meet your home's temperature settings. The code will disappear automatically once your home reaches the desired temperature and the thermostat switches off.

DIY fix possible

Check if your room thermostat is set to a high temperatureEnsure your central heating programmer or timer is switched to 'On'Check if your hot water cylinder thermostat is calling for heat

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Related fault codes

D.0View →

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