How much does it cost to fix Unical error code 27?

Typical repair cost for the Unical 27 fault is £150-250 including labour.

27 High

Unical 27 Fault Code

Q: What does the Unical 27 fault code mean?

Your boiler has detected that the water temperature is rising much faster than expected, which usually points to a restricted flow or a problem with the internal circulation pump.

The Unical 27 fault code means: your boiler has detected that the water temperature is rising much faster than expected, which usually points to a restricted flow or a problem with the internal circulation pump.. It appears on 2 Unical models in our database.

Technical description: ERROR Flow Gradient

Typical repair cost £150-250 (including labour)

Engineer required

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

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Unical models that show the 27 fault code

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

Source

Unical 27 fault code information on this page is sourced and cross-checked against the official Unical service / installation manuals for each affected model.

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