GOLD 1–5 and GOLD A:

1. Press and hold the PROG button for 6 seconds. 

2. Press the FLOW button for 1 second, without releasing the PROG button. 

3. Press and hold the PROG button for a further 8 seconds until SERVICE appears on the display.

4. Release the button.

GOLD B:

Go to the INST buttons, and then FLOW. Now press buttons 1 + 4 simultaneously to go forward to the start menu for the functions, alarm, cooling, manual test operation, reading and regulation settings. 

You will also find the description in Operation & Maintenance.