Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
CH Demand
Gain access to PCB (use Insulation Mat as required)
Operating Switch in Heating & Water position.
Operating Switch in Heating & Water position.
Gas On
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Is there Mains present across Connector N4 connection ML (Brown) on Ignition Control board and Terminal block X4 connection 2 (N Blue) on Main Driver board?
Note:
Voltage will not be present before main burner ignites.
Note:
Voltage will not be present before main burner ignites.
Isolate as per TOPs P4
and refit as necessary