Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
CH Demand
Attach pressure gauge to the inlet pressure test point
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset boiler if required.
Set boiler to maximum rate CLICK HERE FOR GUIDE
Does the pressure gauge show an inlet pressure of 14 mb or greater throughout the operation?
Note:
1. The manufacturer states the boiler range is able to deliver its full output
at inlet pressures as low as 14mb, however please refer to British Gas Technical
Operational Procedures for further guidance regarding gas inlet working pressures.
2. When pressure gauge is removed test point should be tightened and checked for gas tightness.
3. Refer to data plate / MI's for LPG pressures.