Medium
S.53 on Vaillant ecoFIT Pure 830

Your boiler has temporarily stopped because it cannot move water around your heating system efficiently, likely due to low pressure or an internal blockage.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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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

Product in waiting period/operation block function due to low water pressure (flow/return spread too large)

From this model's manual
Verified against the Vaillant Ecofit Pure 830 installation & service manual, page 33.
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 the pressure gauge on the front of the boiler; if it is below 1.0 bar, use the internal filling loop to top it up to 1.5 bar.Ensure all radiator valves are fully open to allow water to flow freely.Restart the boiler once the pressure is at the correct level.

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