Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Ensure left hand filling tap CLOSED
Turn right hand filling tap to the OPEN position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Observe the appliance does the demand for HW stop?
Note:
Image shows the filling loop tap in the closed position.