Set Appliance State:
Mains Power Off
Set Multimeter to AC Volts 
Water heater switch set to constant
Set thermostat to MID position
Set thermostat to MID position
Gas On
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Allow burner to ignite, system to run and reach set temperature.
Does thermostat operate when temperature is reached?
To detect operation of thermostat measure the voltage across connection 4 (blue lead) and connection 24 (yellow lead) on the control module.
Note: Before operation voltage will be present, after operation no voltage will be present.
Does thermostat operate when temperature is reached?
To detect operation of thermostat measure the voltage across connection 4 (blue lead) and connection 24 (yellow lead) on the control module.
Note: Before operation voltage will be present, after operation no voltage will be present.
Isolate as per TOPs P4
and refit as necessary