Set Appliance State:
Set Multimeter to DC Volts 
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Mode Selector Switch to DHW position
Attach a U-gauge to the pressure test point
Mode Selector Switch to DHW position
Attach a U-gauge to the pressure test point
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Is there a voltage greater than 9V DC measured at the Modulation Coil (Purple + Grey)?
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.
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