High
Overheat thermostat on Grant Vortex Pro 15-26

Your boiler has switched itself off because it has become dangerously hot, likely due to a circulation problem or a system blockage.

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

Automatically switch off the boiler if the heat exchanger exceeds a pre-set temperature of 111°C ± 3°C.

From this model's manual
Verified against the Grant Vortex Eco installation & service manual.
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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