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

Your boiler is struggling to detect enough water flowing through the system to operate safely.

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

Watercirculationvol.actualvalue

From this model's manual
Verified against the Vaillant Ecotec Pro Ecotec Plus System installation & service manual, page 56.
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 are fully openEnsure your system pressure is at the recommended level of 1.0 to 1.5 barCheck if your external pump is running or if the isolation valves beneath the boiler have been accidentally closed

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