High
16 on Unical Alkon C 28 HE

Your boiler has temporarily locked out because the internal temperature has dropped dangerously close to freezing, which risks damaging the heat exchanger.

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

EXCHANGER FREEZING ( 24 ) Exchanger freezing is detected If the heating sensor detects a temperature below 2° C, burner ignition is inhibited until the sensor detects a temperature above 5°C. Disconnect the from the power supply, close the gas valve, defrost the exchanger carefully.

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 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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Related fault codes

24View →

All 33 fault codes on the Alkon C 28 HE

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

14568091112131415171820212223242627303233384344455355758081

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