Medium
d.78 on Vaillant ecoTEC Pro / ecoTEC Plus

Your boiler has detected that the water inside the hot water storage tank is getting hotter than the safety limit allowed, so it has temporarily paused heating to prevent overheating.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

Storage charging temperature limit

From this model's manual
Verified against the Vaillant Ecotec Combi installation & service manual, page 46.
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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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