Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
Selector Switch in DHW Summer position
Hot Water Thermostat set to Maximum
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Following Ignition the Burner should go to full flame.
After allowing the Boiler to heat up for at least 1 minute, slowly reduce the HW Thermostat Control Setting until a 'click' is heard. The burner will drop to a low flame.