BoilerFaultCodesTechnical description
Short-circuiting in the 24 V circuit (three-way valve or connector); check for a short-circuit and replace the F3 fuse in the control panel.
What causes this fault?
This fault occurs when an internal electrical component, usually the motor that moves between heating and hot water, develops a fault and draws too much power. This surge causes a protective fuse on the main control board to blow, which cuts power to the boiler to prevent further damage. The most common root cause is water or moisture entering the three-way valve motor, causing it to short out.
This issue often surfaces in autumn when the heating is turned on for the first time after summer, as the three-way valve may have seized from lack of use.
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.