F.327 Medium

Vaillant F.327 Fault Code

Also written as F327 — same fault.

The Vaillant F.327 fault code means: your boiler has detected that it is set up to provide hot water to a storage tank that isn't currently connected, causing it to limit how much water flows through your heating system.. It appears on 3 Vaillant models in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: The minimum heating volume flow is limited due to there being no domestic hot water circuit connected.
Typical repair cost £120-200 (including labour)

Engineer required

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

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Vaillant models that show the F.327 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Vaillant F.327 fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026