F.78 - DHW outlet sensor interruption at external controller

What does F.78 mean?

There is an interruption in the Domestic Hot Water (DHW) outlet sensor when an external controller is connected. This typically occurs if a UK link box is used, but the hot water NTC is not bridged.

• UK link box is connected, but the hot water NTC (Negative Temperature Coefficient) sensor is not bridged.

Click steps to track your progress.

1. 1

   Press the reset button on the boiler display up to three times to try and clear the fault.

2. 2

   If a UK link box is installed, ensure the hot water NTC sensor is correctly bridged. This is typically an installer task.

3. 3

   Contact customer service or the installer to verify the wiring configuration related to the external controller and DHW sensor.