Set Appliance State:

Mains Power Off
Gas Off
Set Multimeter to AC Voltage Set meter to measure AC Volts
CH Demand
Selector Switch in Winter (II) position
Remove connector J2 from PCB.
Clip multimeter to J2 pins 1 (right) and 2 (centre).
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

!! Mains Power OFF and replace connector on
the Centre and Right hand pins !!
Note!
no connection on Left hand pin !!