Emergency
GTH90 on Grant Vortex

Your boiler has detected that exhaust gases are not escaping properly, likely because the flue outside is obstructed or damaged.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

What the manual says

Manufacturer manual

High level terminal

From this model's manual
Verified against the Grant Vortex installation & service manual, page 21.
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 emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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GTH80View →GTH100View →

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