Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove the Hot Water micro switch from the boiler
Measurement:
Test 1:
Measure the resistance between the two exposed terminals of the hot water flow switch.
Expect open circuit.
Test 2:
Make the switch by pressing with your finger.
Expect continuity / zero resistance.
Are the resistances as expected?
Measure the resistance between the two exposed terminals of the hot water flow switch.
Expect open circuit.
Test 2:
Make the switch by pressing with your finger.
Expect continuity / zero resistance.
Are the resistances as expected?
Isolate as per TOPs P4
and refit as necessary