Set Appliance State:
Set Multimeter to DC Volts 
CH temperature switch to minimum
DHW temperature switch to maximum
DHW temperature switch to maximum
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage across connection 5 (green wire) and connection 3 (red wire) on connector X4 on the PCB.
Approximately 12 vdc should be present.
Is the voltage as expected?
Approximately 12 vdc should be present.
Is the voltage as expected?
Isolate as per TOPs P4
and refit as necessary