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)
Selector switch in CH & HW mode
Ensure no DHW demand
Selector switch in CH & HW mode
Ensure no DHW demand
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Allow boiler to carry out ignition sequence and burner to ignite.
Approximately 5 seconds after the burner establishes measure the voltage between pin 5 (blue) and
pin 6 (black) wires of X3 on the main PCB.
Mains voltage should be present.
Approximately 5 seconds after the burner establishes measure the voltage between pin 5 (blue) and
pin 6 (black) wires of X3 on the main PCB.
Mains voltage should be present.
Isolate as per TOPs P4
and refit as necessary