Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove leads from heat exchanger overheat stat
Measurement:
Measure for resistance across the terminals of the heat exchanger overheat stat.
Expected resistance short circuit.
Is resistance as expected?
Expected resistance short circuit.
Is resistance as expected?
Isolate as per TOPs P4
and refit as necessary