Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
Turn Hot Water Tap On
Mode Selector Switch to DHW position.
Turn C/H stat to max and DHW to minimum.
Connect a U-gauge to the pressure test point on the Gas Valve.
Turn C/H stat to max and DHW to minimum.
Connect a U-gauge to the pressure test point on the Gas Valve.
Gas On; Pilot On
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Allow the boiler to run for approximately 1 minute.
Measure a modulation voltage less than 1V DC across the Modulation Coil (Purple + Grey wires).
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.
Measure a modulation voltage less than 1V DC across the Modulation Coil (Purple + Grey wires).
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.
Isolate as per TOPs P4
and refit as necessary