Set Appliance State:
Gas Off
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
CH Demand
Boiler ON/OFF Switch OFF
CH Temperature Selector to Max
DHW Temperature Selector OFF
Remove lower front facia panel
CH Temperature Selector to Max
DHW Temperature Selector OFF
Remove lower front facia panel
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Boiler ON/OFF Switch ON.
Check for Mains Voltage across Terminal marked Lr and Terminal marked Ns at connector marked ST8 on the main PCB.
Check for Mains Voltage across Terminal marked Lr and Terminal marked Ns at connector marked ST8 on the main PCB.
Isolate as per TOPs P4
and refit as necessary