BoilerFaultCodesAlpha E78 Fault Code
The Alpha E78 fault code means: your boiler is struggling because the water inside is not circulating properly, causing a significant temperature difference between the water leaving and returning to the unit.. It appears on 18 Alpha models in our database.
Technical description: High flow/return temperature differential
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Alpha models that show the E78 fault code
Click a model for the full fault code list and model-specific repair notes.
- C25 Xtraflame Repair: £150-350
- E-Tec Repair: £150-250
- E-Tec 24 Repair: £150-250
- E-Tec 28 Repair: £150-250
- E-Tec 33 Repair: £150-250
- E-Tec Plus Repair: £150-250
- E-Tec Plus 24 Repair: £150-250
- E-Tec Plus 28 Repair: £150-250
- E-Tec Plus 33 Repair: £150-250
- E-Tec R Repair: £150-250
- Evoke Repair: £150-300
- Evoke 10 / 18 Repair: £220-380
- H25 Xtraflame Repair: £150-350
- Intec 28GS Repair: £150-350
- Intec 40GS2 Repair: £150-300
- Intec 50CS Repair: £150-350
- Pro Tec 24 Repair: £150-300
- Pro Tec Plus Repair: £150-300
Source
Alpha E78 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