Set Appliance State:
Gas Off
Set Multimeter to DC Volts 
CH Demand
Isolate Mains Power to appliance as per TOPs P4
Remove the Sense Electrode Lead (1) from the Burner Flame Sensing Electrode and attach the positive voltmeter lead to the Sensing Electrode and the negative voltmeter lead to the Gas Valve Earth connection Green/Yellow wire).
On/Off Switch On.
Remove the Sense Electrode Lead (1) from the Burner Flame Sensing Electrode and attach the positive voltmeter lead to the Sensing Electrode and the negative voltmeter lead to the Gas Valve Earth connection Green/Yellow wire).
On/Off Switch On.
Gas On
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
After approximately 20 seconds (boiler purge period) ignition should occur, the Burner should ignite and the Sense Electrode should provide a DC voltage on the meter.
Reconnect Lead.
Note:
Shortly after the Burner has lit it will go out because the Sense Electrode Lead is disconnected.
Reconnect Lead.
Note:
Shortly after the Burner has lit it will go out because the Sense Electrode Lead is disconnected.
Isolate as per TOPs P4
and refit as necessary