Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Ensure there is no demand for either CH or DHW
Set Multimeter to DC Volts 
Disconnect and make safe the 4 wire low
voltage connector from the fan
voltage connector from the fan
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Reset appliance if it is in lockout.
Measure the DC voltage between the Green and
Blue wires in plug X23 on the PCB.
Expect approximately 0V DC.
Open a hot water tap then repeat the above measurement.
Expect approximately 24V DC.
Note:
Voltage will not change if appliance returns to lockout, reset as necessary until test is complete.
Measure the DC voltage between the Green and
Blue wires in plug X23 on the PCB.
Expect approximately 0V DC.
Open a hot water tap then repeat the above measurement.
Expect approximately 24V DC.
Note:
Voltage will not change if appliance returns to lockout, reset as necessary until test is complete.
Isolate as per TOPs P4
and refit as necessary