Medium
D.029 on Vaillant ecoTEC Pro / ecoTEC Plus Combi

Your boiler is measuring the speed at which water flows through your heating system, and it has detected that the flow is currently too slow.

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

Water circulation vol. actual value

From this model's manual
Verified against the Vaillant Ecotec Pro Ecotec Plus Combi installation & service manual, page 41.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check that all radiator valves throughout your home are fully open.Ensure your system pressure is set correctly, typically between 1.0 and 1.5 bar on the gauge.Bleed your radiators to remove any trapped air that might be blocking the water flow.

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