High
78 on Vokera Linea One

Your boiler is struggling to manage the temperature difference between the water leaving the heater and the water returning to it, causing the system to stop working properly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

flow/return ΔT error (2nd CH)

From this model's manual
Verified against the Vokera Linea One installation & service manual, page 31.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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