Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
Set the DHW flow rate at the tap to approximately 3.0 l/min (0.7gall/min )
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow boiler to ignite and heat the DHW to approximately 65 °C.
Does the fan speed reduce as the temperature demand is met?