Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
Turn Hot Water Tap On
Gain access to PCB (use Insulation Mat as required)
Heating temperature selector to OFF
Programmer or selector switch set to hot water only
Hot water temperature selector to maximum
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure voltage across connection 3 (brown wire) and connection 2 (blue wire) at connector X7 on the main PCB.
With no CH demand there should be no voltage present.