Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
DHW Demand
Selector Switch to Hot Water and Heating
Remove the spark igniter cap and place below
the igniter against the heat exchanger as shown
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow self check to complete and ignition sequence to commence.
DO NOT hold the igniter.
Watch for sparking from the igniter lead to the heat exchanger case.
Note:
Ensure the electrode lead is placed close to the heat exchanger casing for sparking to occur.