Low
d.70 on Vaillant Home System

Your boiler is currently set to a specific service mode that forces the internal valve into a fixed position rather than operating normally.

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

Operation of the diverter valve: 0=Normal operating mode (DHW and heating mode), 1=Mid-position (parallel operation), 2=Permanent setting: He

From this model's manual
Verified against the Vaillant Home System installation & service manual.
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

Press the Menu button on the control panelNavigate to the Installer Level or Settings menuLocate setting d.70 and change the value back to 0Confirm and exit the menu to restore normal operation

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d.00View →d.01View →

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