High
27 on Alpha Intec 40GS2

Your boiler is struggling to circulate water properly, causing the system to overheat almost instantly, which means it has shut down to protect itself from damage.

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 primary flow - Rapid temperature rise of primary sensor

From this model's manual
Verified against the Alpha Intec 40gs2 installation & service manual, page 42.
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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