Riello PRESS 140 T/N Installation, Use And Maintenance Instructions page 11

Thermostat for adjustment - maximum value - minimum value
Electronic adjustment thermostat By means of information relayed from a PT100 probe immersed in the oil in the
delivery manifold, the thermostat adjusts spray temperature. (The correct conditions for fuel spray are shown in the
temperature/viscosity graph below).
2
mm /s °E
Example: fuel oil with 7 °E viscosity at 50 °C is pre-heated to approximately 110 °C.
Note: although the temperature set on the thermostat should correspond to the temperature of the fluid, it is good
practice to check that the thermometer shows the correct reading once the unit has been in operation for a few
minutes.
The LED will illuminate to indicate that the heating resistances are working properly.
Minimum temperature thermostat. In addition to shutting down the burner if the fuel temperature should fall below the
critical value for correct combustion, this thermostat also provides a permissive signal at the time of burner start-up.
(Factory set at approximately 80°C, adjustable by removing the pre-heater cover and relative plate).
Maximum temperature thermostat. This switches off the resistance when, because of failure of the adjustment ther-
mostat, the temperature of the pre-heater increases to unacceptable levels; a "high temperature" alarm output is
provided on the burner terminal strip. (Factory setting is approximately 180°C).
Renewing the minimum and maximum temperature thermostats.
Reposition the probes of the new thermostat, after having first loos-
ened the plate pack securing screws. Make sure that the probe is
touching the resistance and the plate pack as shown in the adjacent
figure. The same precautions should be taken when renewing the re-
sistances in contact with the thermostat probes.
If the pre-heater should malfunction, use an ohmmeter to check that
the resistances located in contact with the temperature probes are not
burnt out (reading of approximately 35 Ohm).
Changing the PT100 probe in the oil delivery manifold:
Fit the supplied nut and biconical collar on the new probe, insert a
length of approximately 40 mm in the manifold, and secure firmly into place.
At this point, the section remaining outside the manifold can be bent as required, with no risk of damaging the re-
sistance.
5831
SPRAY TEMPERATURE ADJUSTMENT
Atomisation temperature
10
Adjustment thermostat probe
Thermometer
Min. temperature thermostat
Pre-heater
Max. temperature thermostat
Purge
Tubes into aluminium plate
Aluminium
plate
Thermostat probe
Resistance