Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
CH temperature control to max
Selector switch set to ch/dhw
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 5 minutes with the central heating demand.
Remove CH demand.
Does the pump continue to run for approximately 30 seconds?