How much does it cost to fix Alpha error code 26?

Typical repair cost for the Alpha 26 fault is £250-450 including labour.

26 High

Alpha 26 Fault Code

Q: What does the Alpha 26 fault code mean?

Your boiler has detected that the core part responsible for heating your water is failing to transfer heat properly, causing the system to shut down for safety.

The Alpha 26 fault code means: your boiler has detected that the core part responsible for heating your water is failing to transfer heat properly, causing the system to shut down for safety.. It appears on 1 Alpha model in our database.

Technical description: Main heat exchanger

Typical repair cost £250-450 (including labour)

Engineer required

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

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Alpha models that show the 26 fault code

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

240XE Repair: £250-450

Source

Alpha 26 fault code information on this page is sourced and cross-checked against the official Alpha service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026