Medium
154 on Atag iR15

Your boiler has detected an abnormal temperature difference between the water leaving it and the water returning, which usually indicates a circulation problem inside the system.

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

Flow increases to fast ∆T to large, return > flow

From this model's manual
Verified against the Atag/Atag Ir Regular installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

153View →155View →133View →

All 15 fault codes on the iR15

Seeing a different code? Every code this model can display, in one place.

1020405061105110111119129133151180181

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