Set Appliance State:

Ensure NO demands
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset the appliance (press and hold power button for 4 seconds then release)
The appliance will then start a self check program which lasts for 1.5 minutes.
While the self check completes set the appliance to DHW and CH mode (radiator and tap symbol in display - toggle modes by pressing the "mode" button)
Monitor the appliance for the full 1.5 minutes before selecting an outcome.
If a fault code is shown at the end of the 1.5 minute self check click here.