Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Disconnect compensation tube from gas valve
Attach pressure gauge to gas valve pressure outlet test point
Ensure boiler is cool
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Measure the burner pressure as burner ignites.
There should be a positive burner pressure that slowly
increases as the gas valve "soft light" function operates.
The pressure may not reach operating pressure if it is not establishing
but it should be significantly above minimum pressure (refer to Table 1).
Notes:
1. Reset as necessary until test is complete.
2. When pressure gauge is removed the pressure test point
should be tightened and checked for gas tightness.