Set Appliance State:
Mains Reset Switch OFF
Set Multimeter to AC Volts 
Isolate Mains Power to appliance as per TOPs P4
Ensure the boiler is cool so that there is demand for preheat
Set DHW temperature switch to ECO
Remove rear control panel cover to expose main PCB
Ensure the boiler is cool so that there is demand for preheat
Set DHW temperature switch to ECO
Remove rear control panel cover to expose main PCB
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Mains reset switch On.
Measure voltage across the live (brown lead) and neutral
(blue lead) connection on the connector marked H1 on
the main PCB.
Mains power Off.
Measure voltage across the live (brown lead) and neutral
(blue lead) connection on the connector marked H1 on
the main PCB.
Mains power Off.
Isolate as per TOPs P4
and refit as necessary