Set Appliance State:

Mains Power Off
CH Demand
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow the boiler to operate and reach maximum temperature.
Switch off CH demand.
Does the pump continue to run until the boiler has cooled down sufficiently?
Note:
1. Pump overrun will only operate if the system is fully pumped,
pass this test (select pump overruns) if a gravity system.
Pump overrun is not operational when the appliance is fitted on a gravity system.
2. It may be necessary to reduce the heating load by turning off some radiators.
This will shorten the time required for this test.