Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Voltage Set meter to measure AC Volts
CH Demand
Gain access to PCB (use Insulation Mat as required)
Ensure that the Boiler Thermostat is set to MAX
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the voltage across the two red wires on the PCB connector marked CON 2.