Medium
D.029 on Vaillant ecoTEC plus

Your boiler is struggling to pump water around your radiators effectively, often because the flow of water is being restricted.

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

Heatingcircuitflowrate

From this model's manual
Verified against the Vaillant Ecotec Plus installation & service manual, page 74.
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, usually between 1.0 and 1.5 bar.Bleed your radiators to remove any trapped air that might be blocking the water flow.

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like D.029: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related fault codes

F.22View →F.75View →

Related guides you might find useful

No hot water but heating works

Almost always a stuck diverter valve on combis.

Read →

Banging / kettling / whistling noise

Each noise points to a different fault.

Read →

Radiators cold at the bottom

Sludge build-up — needs flushing, not bleeding.

Read →