Set Appliance State:

Mains Power Off
On/Off Switch OFF
Turn Hot Water Tap On
CH temperature switch to minimum
DHW temperature switch to maximum
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Turn On/Off switch to On.
The following sequence should occur:
Fan runs
Sparking present
Burner ignites
DHW runs hot
Please select area of fault.