Set Appliance State:

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

Observation:

Appliance On/Off control set to On position.
Reset lockout as necessary.
Allow the burner to ignite and establish.
With a flow rate at the tap of 8.5 litres/minute is there a temperature rise of 40°C?