Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Attach temperature clamps to flow and return pipes as shown
Ensure DHW store is not up to temperature (below 40°C) - Run off water from hot tap as necessary
DHW temperature set to MAX
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Ensure all hot water taps are off.
Apply DHW demand.
Allow boiler to run for at least 2 minutes while monitoring the differential between the flow and return pipes.
Differential should be approximately 15°C or less.