Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Attach pressure gauge to fan pressure test point
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Fan pressure should reach approximately -2.1 mbar or greater.
Notes:
1. The pressure measured will be negative.
2. When pressure gauge is removed pressure point cap should be replaced.