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)
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Cancel purge cycle & If required, reset boiler.
Allow the boiler to operate for CH.
Measure the A/C voltage across the outer pins
(brown and blue) of connector CN4.
Mains voltage should be present.
Allow the boiler to operate for CH.
Measure the A/C voltage across the outer pins
(brown and blue) of connector CN4.
Mains voltage should be present.
Isolate as per TOPs P4
and refit as necessary