Set Appliance State:

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

Measurement:

Measure for AC voltage across pin 1 of connector X14 and a suitable earth connection.
Expect voltage 240Vac (mains voltage).
Note.
1. It may take approximately 40 seconds for the boiler to recognise a demand, this will depend upon the boiler status.
(Status code guidance CLICK HERE)
2. Ensure a good connection is made on connector X14.