Medium
23 on Sime Murelle EV HE System

Your boiler is having trouble communicating with the secondary heating circuit that controls a specific part of your home, such as an underfloor heating zone.

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

ANOMALY SECOND MIXED ZONE

From this model's manual
Verified against the Sime Murelle Ev He Combi installation & service manual, page 32.
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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