Low
43 mm on Ferroli F24b

This is a technical configuration setting for your boiler's flue rather than a system fault, indicating the specific size of the air restrictor plate required for your flue pipe setup.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Restrictor size for Concentric 1 bend + 1 meter

From this model's manual
Verified against the Ferroli F24b installation & service manual, page 16.
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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