Set Appliance State:

Mains Power Off
DHW Demand
DHW Selector in Maximum (+) position
CH Selector in Minimum (-) position
ON/OFF Switch in ON position
Remove the vent plug from the pump.
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Remove the vent screw from the front of the pump and observe the spindle.
CAUTION: Water may be emitted from the end of the pump, be sure to protect the work area while undertaking this test.
Does the pump run?
Note: Do not take sound or vibration as indication pump is running.