Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
DHW Demand
DHW Selector in Maximum (+) position
CH Selector in Minimum (-) position
ON/OFF Switch in ON position
Gas Off
Attach pressure gauge to the inlet pressure test point
The inlet pressure test point is the left hand of the two ports
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Ensure no other gas appliances are in use.
Allow the ignition sequence to commence.
A drop in the standing pressure should be seen as the gas valve opens.
Notes:
1. When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.
2. No other gas appliances must be in use during the test. The appliance will have 5 ignition attempts approximately 5 seconds apart and gas will only pass for approximately 3 seconds on each ignition attempt.