Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
DHW Demand
Selector Switch to Hot Water and Heating
Gain access to PCB (use insulation mat as necessary)
Gain access to PCB (use insulation mat as necessary)
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Check AC voltage at connector X3 pins 5 (Black) and 7 (White).
Expect mains voltage.
Expect mains voltage.
Isolate as per TOPs P4
and refit as necessary