Set Appliance State:

Mains Power Off
DHW Demand
Pump is not an integral part of the appliance and will be located else where
Gas On
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Allow the boiler to run for one minute with the central heating demand.
Remove CH demand.
Does the pump continue to run for approximately 2 minutes?