Set Appliance State:

Mains Power Off
Gas Off
Mode selector switch to Off/Reset position
Turn Hot Water Tap ON
Hot water temperature control set to maximum
Attach U-gauge to burner pressure test point
Remove protective cover from the gas valve adjustment screw
Gas On
WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Mode selector switch to DHW position.
Allow burner to ignite.
With a DHW demand is the burner pressure satisfactory? Maximum burner pressure should be approximately 10.1 mbar (plus or minus 1 mbar).
Refit protective cover to the gas valve adjustment screw
Note: When U-gauge is removed pressure nipple should be tightened & checked for gas soundness.