High
Er18 on Biasi Concept 400 20 1 Mfs

Your boiler has detected an issue with the water flow around your radiators, suggesting the pump that pushes water through your heating system is not working correctly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

External pump / C.h. circuit - check External pump, C.h. circuit

From this model's manual
Verified against the Biasi Bm Biasi Concept 400 20 1 Mfs installation & service manual, page 10.
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 is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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