30 Medium

Alpha 30 Fault Code

The Alpha 30 fault code means: your boiler has detected that the water leaving it is significantly hotter than the water returning, suggesting a circulation problem in your heating system.. It appears on 2 Alpha 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: Temperature difference between system flow and return too high
Typical repair cost £120-250 (including labour)

DIY fix possible

Check that all radiator valves throughout your home are fully openEnsure your central heating pump is operating and not seizedCheck for any blockages or airlocks in your system that might be restricting flow

Find a Gas Safe engineer

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Alpha models that show the 30 fault code

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

Source

Alpha 30 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 31 August 2026