Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
CH Demand
Gain access to PCB (use Insulation Mat as required)
Gas On
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Ensure external controls are calling for heat and allow the boiler to enter its ignition sequence.
During the ignition sequence monitor the voltage to earth on the white wire at pin 9 of PCB connector X20.
Once the fan starts there should be approx. 13Vdc at the White wire.
During the ignition sequence monitor the voltage to earth on the white wire at pin 9 of PCB connector X20.
Once the fan starts there should be approx. 13Vdc at the White wire.
Isolate as per TOPs P4
and refit as necessary