Set Appliance State:

Boiler DHW thermostat set to MAX
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Enable preheat by pressing both buttons on the left hand side until display alternates "cF" and "on".
The burner should ignite and the appliance should heat to approximately 75°C the burner should then extinguish.
Note:
To disable preheat press the buttons on the left hand side again until display alternates "cF and "oF".