Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Remove the connector from the return thermostat
Measurement:
Measure the resistance between the thermostat on the heat exchanger
flow pipe and a suitable ground point on the appliance (i.e. the return pipe).
flow pipe and a suitable ground point on the appliance (i.e. the return pipe).

Isolate as per TOPs P4
and refit as necessary