Riello 3438964 Installation, Use And Maintenance Instructions page 47

4.6 SPRAY TEMPERATURE ADJUSTMENT
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).
Adjustment thermostat probe
Thermometer
2
mm /s °E
D2746
Min. thermostat
D2747
°C
Pre-heater
Spray temperature
Purge Max. thermostat
Example: fuel oil with 7 °E viscosity at 50 °C is pre-heated to approximately 110 °C.
Important: 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 adjust-
ment thermostat, 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 hav-
Tubes into aluminium plate
ing first loosened 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 resist-
Aluminium
plate
ances in contact with the thermostat probes.
If the pre-heater should malfunction, use an ohmmeter
Resistance
to check that the resistances located in contact with the
temperature probes are not burnt out (reading of ap-
proximately 35 Ohm).
Changing the PT100 probe in the oil delivery manifold.
Fit the supplied nut and biconical collar on the new
D2751
Thermostat probe
probe, insert a length of approximately 40mm in the man-
ifold, and secure firmly into place. At this point, the sec-
tion remaining outside the manifold can be bent as
required, with no risk of damaging the resistance.
2915844
13 GB