Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
Turn Hot Water Tap On
Gain access to PCB (use Insulation Mat as required)
DHW temperature selector to Max
DHW temperature selector to Max
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage between the grey wires on connector CN1 at the PCB.
Shortly after the pump begins to run the voltage
should drop from between 5 - 35V DC to approximately 0V DC.
Continue to monitor the voltage until the boiler cuts out.
Does the voltage change back to 5 - 35V DC indicating the
flow switch has cut out or does the voltage remain at 0V?
Shortly after the pump begins to run the voltage
should drop from between 5 - 35V DC to approximately 0V DC.
Continue to monitor the voltage until the boiler cuts out.
Does the voltage change back to 5 - 35V DC indicating the
flow switch has cut out or does the voltage remain at 0V?
Isolate as per TOPs P4
and refit as necessary