Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
CH Demand
Attach temperature clamp to flow pipe
Set boiler temperature control to maximum
Set boiler temperature control to maximum
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Allow appliance to fire and system to heat.
Measure for dc voltage between overheat stat and pcb connection as illustrated.
(There are different versions of pcb used in this appliance)
Expected voltage between 30 - 40 vdc.
Note.
To speed up the process reduce the heating circuit by turning some rads off.
Observe both temperature and voltage readings.
Choose from the following observations.
BOILER MAINTAINS OR SHUTS DOWN AT 75 - 90°C, VOLTAGE PRESENT
VOLTAGE DISAPPEARS, BOILER GOES TO OVERHEAT, TEMP 90°C or BELOW
VOLTAGE PRESENT, TEMP AT 90°C AND BOILER STILL FIRED
Measure for dc voltage between overheat stat and pcb connection as illustrated.
(There are different versions of pcb used in this appliance)
Expected voltage between 30 - 40 vdc.
Note.
To speed up the process reduce the heating circuit by turning some rads off.
Observe both temperature and voltage readings.
Choose from the following observations.
BOILER MAINTAINS OR SHUTS DOWN AT 75 - 90°C, VOLTAGE PRESENT
VOLTAGE DISAPPEARS, BOILER GOES TO OVERHEAT, TEMP 90°C or BELOW
VOLTAGE PRESENT, TEMP AT 90°C AND BOILER STILL FIRED
