Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
Selector switch to DHW position
CH temperature selector to minimum
DHW temperature selector to maximum
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset appliance as necessary.
With DHW demand does the pump run?
Do not take sound or vibration as an indication of the pump running.