Set Appliance State:

Mains Power Off
Gas Off
Set Multimeter to AC Voltage Set meter to measure AC Volts
Selector Switch in Winter (II) position
Ensure Timer is switched on, if fitted.
Turn Room Thermostat for maximum heat.
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Connect meter between terminal 2 (N) and terminal 4,
measure mains voltage.