Set Appliance State:
Mains Reset Switch OFF
Set Multimeter to DC Volts 
Isolate Mains Power to appliance as per TOPs P4
Ensure the boiler is cool so that there is demand for preheat
Set DHW temperature selector to ECO
Disconnect J4 connector at PCB and make safe
Ensure the boiler is cool so that there is demand for preheat
Set DHW temperature selector to ECO
Disconnect J4 connector at PCB and make safe
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Mains reset switch ON.
Measure voltage across the red and blue leads
(terminals 1 and 5).
Expected voltage approximately 37 volts DC.
Measure voltage across the red and blue leads
(terminals 1 and 5).
Expected voltage approximately 37 volts DC.
Note:Test shall be carried out with connector in-situ, attached to the fan.
 connector dc.gif)
Isolate as per TOPs P4
and refit as necessary