High
H.01.05 on Baxi Assure System

Your boiler has detected that the water leaving it is significantly hotter than the water returning, suggesting that heat isn't circulating properly through your radiators.

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

INSUFFICIENT CIRCULATION Maximum temperature difference value between flow and return reached. Check the boiler/installation circulation Activate a manual venting cycle Check the installation pressure Check the cleanliness of the exchanger Check the operation of the temperature sensors Check the connection of the temperature sensors

From this model's manual
Verified against the Baxi Bm Baxi B Basic System 2 600 800 Assure 500 Isim installation & service manual, page 48.
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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