Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
Gain access to PCB (use Insulation Mat as required)
Hot tap ON
Function selector in standby position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Function selector to DHW position.
Allow fan to start.
After approximately 5 seconds measure voltage across the blue (neutral) and brown (live) leads on connector marked X17 on the PCB.
Expected voltage mains voltage (240 VAC).
Voltage will only be present for approximately 4 seconds as flame will not prove.