Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
DHW temperature control set to maximum
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Appliance On/Off control set to ON position.
Reset lockout as necessary.
Allow the fan to run and the ignition sequence to commence.
With a DHW demand does sparking occur and the burner ignite?