Low
D.078 on Vaillant ecoTEC Pro 28

Your boiler is temporarily limiting the heat of the water it produces to prevent the system from getting too hot while you are using the taps or shower.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

DHW max. flow temperature

From this model's manual
Verified against the Vaillant Ecotec Pro installation & service manual, page 44.
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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