Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
Turn Hot Water Tap On
Disconnect the green wire (normally open connection) from the air pressure switch and make safe
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Allow fan to run.
Measure the AC voltage between the exposed metal spade terminal on the air pressure switch and a suitable earth point.
Expect approximately 6 Volts AC or greater.
Measure the AC voltage between the exposed metal spade terminal on the air pressure switch and a suitable earth point.
Expect approximately 6 Volts AC or greater.
Isolate as per TOPs P4
and refit as necessary