Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset appliance if required (rotate selector switch to
'O' position, then rotate back to DHW/CH position).
Allow self-check to complete.
Can sparking be seen through the sight glass?
Does the burner ignite and establish smoothly?
Note:
If air flow fault code (70 deg flashing) shows during test click HERE.