Set Appliance State:

Set Multimeter to AC Volts Set meter to measure AC Volts
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Remove plastic cover from the ignition control PCB attached to the gas valve
Selector switch to hot water position
CH temperature selector to minimum
DHW temperature selector to maximum
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow fan to run.
Check for mains voltage across connection 7 (live, brown wire) and connection 11 (neutral, blue wire) on ignition PCB.
Note:
Connections are numbered from the top (1) to the bottom (12).