Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect the common wire from the thermostat
Turn Cylinder Thermostat to its MAX setting
Turn Cylinder Thermostat to its MAX setting
Measurement:
Measure the resistance between the common and satisfied terminals of the thermostat.
The resistance measured should be open circuit (O.L).
Note:
The colour and position of the wires will vary between systems and components.
The resistance measured should be open circuit (O.L).
Note:
The colour and position of the wires will vary between systems and components.
Isolate as per TOPs P4
and refit as necessary