Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
CH Demand
Gain access to PCB
Use insulation mat as required
Temperature control to MAX
Ensure boiler is cool
Use insulation mat as required
Temperature control to MAX
Ensure boiler is cool
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
With the fan running measure the DC voltage between the lower white wire (pin 6) at connector J4 on the PCB and a suitable earth point.
Expect approx 6.5V DC.
Expect approx 6.5V DC.
Isolate as per TOPs P4
and refit as necessary