Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
CH Demand
Gain access to PCB (use isolation mat as required)
External controls calling for heat
External controls calling for heat
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage across live return terminal marked LR and the neutral terminal marked Ns at the green terminal block on the PCB.
The terminal block is located at the back of the PCB behind the transformer.
Note:
If a external room stat is not fitted or the integral timer is a wireless control then a link should be present between terminals Ls and Lr.
The terminal block is located at the back of the PCB behind the transformer.
Note:
If a external room stat is not fitted or the integral timer is a wireless control then a link should be present between terminals Ls and Lr.
Isolate as per TOPs P4
and refit as necessary