Low
d.35 on Vaillant ecoTEC sustain

Your boiler is currently reporting the status of the valve that switches your water flow between heating your home and heating your hot water tap.

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

Position of the diverter valve: 0=Heating, 40=Mid-position (parallel operation), 100=Domestic hot water

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F.73View →F.74View →

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