Set Appliance State:

Mains Power Off
Ensure there is a demand to heat the thermal store - this can be achieved by running the DHW with power turned off to the appliance
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow burner to ignite and heating of the thermal store to commence.
Does the thermal store heat get up to temperature and the appliance shut down?