Set Appliance State:

Mains Power Off
Set Boiler Control Thermostat to MAX position
DHW Demand
External controls calling for heat
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Does the pump run?
Select the "Pump runs" option below if the boiler is fitted to a gravity fed system.
Note:
Pump is not an integral part of the appliance.