Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
Turn Hot Water Tap On
Gain access to PCB (use Insulation Mat as required)
DHW Preheat selector to MAX position
DHW Preheat selector to MAX position
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Allow the fan to run.
While the fan is running monitor the voltage between pins 5 and 7 on connector A2 on the PCB.
Does the mains voltage remain constant while the fan is running or does it reduce and fluctuate?
While the fan is running monitor the voltage between pins 5 and 7 on connector A2 on the PCB.
Does the mains voltage remain constant while the fan is running or does it reduce and fluctuate?
Isolate as per TOPs P4
and refit as necessary