Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
DHW Demand
Remove control box cover if necessary
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure voltage between the green at connector X22 with the connector attached to the pcb and the neutral at the incoming mains terminal strip.
Expect approximately 5vdc.
Expect approximately 5vdc.
Isolate as per TOPs P4
and refit as necessary