Emergency
5 on Unical Alkon C 28 HE

Your boiler has automatically shut down because a safety sensor detected that exhaust gases are getting too hot near the flue collector.

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

FLUE GAS COLLECTOR SAFETY THERMOSTAT Intervention of the flue gas collector safety thermostat (23). Rearm the thermostat manually and press the unblock button on the panel. Check the connections.

From this model's manual
Verified against the Unical/Unical Alkon C 28 He 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 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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All 33 fault codes on the Alkon C 28 HE

Seeing a different code? Every code this model can display, in one place.

146809111213141516171820212223242627303233384344455355758081

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