Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
Turn Hot Water Tap On
Gain access to PCB (use Insulation Mat as required)
Selector switch to DHW position
CH temperature selector to minimum
DHW temperature selector to maximum
Selector switch to DHW position
CH temperature selector to minimum
DHW temperature selector to maximum
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Allow fan to run and ignition sequence to commence.
After approximately five seconds:
Test 1: Measure the voltage between connection 38 (Blue wire) and connection 37 (Brown wire) of PCB connector M4.
Test 2: Measure the voltage between connection 38 (Blue wire) and connection 36 (Black wire) of PCB connector M4.
After approximately five seconds:
Test 1: Measure the voltage between connection 38 (Blue wire) and connection 37 (Brown wire) of PCB connector M4.
Test 2: Measure the voltage between connection 38 (Blue wire) and connection 36 (Black wire) of PCB connector M4.
Isolate as per TOPs P4
and refit as necessary