High
d.75 on Vaillant ecoFIT Pure 435

Your boiler has taken longer than it should to heat up your hot water cylinder, which usually means the heat isn't being transferred efficiently from the boiler to the tank.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Maximum cylinder reheating time

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F.22View →F.24View →F.28View →

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