Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
DHW Demand
DHW temperature control to MAX
Measure temp across cold mains inlet and DHW outlet using telegan temperature probes, as close to the combustion chamber as possible
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Allow boiler to ignite and run on DHW
With a flow rate at the tap of approximately 12.3 litres/min is there a temperature rise of approximately 35°C and is operation satisfactory?
Temperature range of DHW is 40-55 °C