Set Appliance State:
On/Off Switch OFF
Set Multimeter to AC Volts 
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Gain access to pcb, use isolation mat as required.
Gain access to pcb, use isolation mat as required.
Gas On
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Appliance On/Off control set to On position.
The fan will run for 2 seconds and stop.
Then measure the voltage at connector ST1 centre pin
(white wire) and a suitable neutral.
The fan will run for 2 seconds and stop.
Then measure the voltage at connector ST1 centre pin
(white wire) and a suitable neutral.
Isolate as per TOPs P4
and refit as necessary