Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
Gain access to PCB (use Insulation Mat as required)
Ensure primary heat exchanger is below 40°C (to ensure a demand for preheat)
Ensure primary heat exchanger is below 40°C (to ensure a demand for preheat)
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
If required reset appliance (press and hold reset button for 5 seconds, then release).
Ensure ECO mode is OFF (press and hold the ECO button until it is no longer illuminated).
This turns the pre heat function ON.
Measure for mains voltage across brown and blue of ST4 pump connector on the PCB.
Ensure ECO mode is OFF (press and hold the ECO button until it is no longer illuminated).
This turns the pre heat function ON.
Measure for mains voltage across brown and blue of ST4 pump connector on the PCB.
Isolate as per TOPs P4
and refit as necessary