BoilerFaultCodesUnical 8 Fault Code
The Unical 8 fault code means: your boiler has stopped working because the water pressure inside the heating system has dropped too low.. It appears on 2 Unical models in our database.
Technical description: WATER DEFICIENCY Insufficient water pressure and consequent intervention of the minimum water pressure - pressure switch ( 13 ). Fill the heating circuit as described in chap. 3.8 and wait for the values to return within default limits. If needed, check the electrical connections and replace the minimum water pressure switch.
DIY fix possible
Locate the filling loop valves beneath the boiler or near the heating pipes.Open the valves slightly to allow mains water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close the filling valves firmly and check the pressure gauge holds steady.
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Unical models that show the 8 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Unical 8 fault code information on this page is sourced and cross-checked against the official Unical service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026