Set Appliance State:

Mains Power Off
Set Multimeter to AC Volts Set meter to measure AC Volts
CH Demand
Summer/Winter Selector to Winter
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the voltage across connection 'Room Thermostat 2' and connection 'N' at the mains input terminal.