Set Appliance State:

Gas On; Pilot On
CH Demand
Isolate Mains Power to appliance as per TOPs P4
On/Off Switch in ON position
Mode Selector Switch to Constant
Heating Thermostat to MAX
Remove both wires from the Modureg
Connect a U-Gauge to the Gas Valve outlet pressure point
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Note:
Ensure that the boiler is cool before testing.
Does the U-Gauge indicate high gas rate pressure and the Burner ignite to a high flame?
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.