Vaillant F.76 Fault Code

What causes the Vaillant F.76 fault?

This fault occurs when the boiler's internal thermal fuse has either failed or detected excessive heat within the primary heat exchanger. It acts as a final safety measure to prevent the appliance from melting or catching fire if other sensors fail to detect an overheat condition. Once this fuse blows or the connection is broken, the electrical circuit is permanently interrupted to ensure the boiler cannot continue operating in an unsafe state.