Set Appliance State:

Mains Power Off
On/Off Switch OFF
CH Demand
External controls calling for heat
CH temperature switch to maximum
DHW temperature switch to minimum
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
Radiators heat
Please select area of fault.