Medium
1P4 on Ariston Clas ONE System

Your boiler has detected that water is not moving around your heating system as efficiently as it should be.

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

Insufficient circulation indication

From this model's manual
Verified against the Ariston Clas One System installation & service manual, page 38.
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 your radiator valves are all fully openEnsure your system pressure is between 1 and 1.5 barBleed any trapped air from your radiators

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