Set Appliance State:
Set Multimeter to AC Volts 
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
CH temperature selector to 0 position
DHW temperature selector to 0 position
CH temperature selector to 0 position
DHW temperature selector to 0 position
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Measure voltage across connection fan live (brown lead) and fan neutral (blue lead) at the fan.
Expected voltage between 220 and 240 volts AC.
Note:
Voltage may only be present for 5 seconds after the appliance On/Off switch has switched on.
Expected voltage between 220 and 240 volts AC.
Note:
Voltage may only be present for 5 seconds after the appliance On/Off switch has switched on.
Isolate as per TOPs P4
and refit as necessary