BoilerFaultCodesUnical 45 Fault Code
The Unical 45 fault code means: your boiler has stopped working because the water pressure inside the system has risen dangerously high above the safe limit.. It appears on 2 Unical models in our database.
Technical description: WATER OVERPRESSURE detected if the H2O pressure Transducer is present with pressure > 2.5 bar; it is reset automatically when H2O pressure < 2 bar. Wait for the values to return to default limits / Replace the Transducer
DIY fix possible
Locate your boiler's filling loop valves or key.Check that both filling valves are fully closed and not letting extra water in.Carefully bleed a radiator in your home to let out excess water until the pressure gauge drops below 1.5 bar.
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Unical models that show the 45 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Unical 45 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