Service manual

Service manual E000129004
7
2.6. Return water temperature sensor
The return temperature sensor has the function of
converting the temperature of the water flowing in the
inlet pipe of the main heat exchanger into an electric
signal (resistance).
F Check
Warning: isolate the boiler from the mains
electricity supply before removing any covering or
component.
1 Remove the cover (section 1.4).
2 Disconnect the connector A (Fig. 18).
3 Measure the resistance between the leads of the
sensor. At a normal temperature of 25 °C the resistance
should be about 12 kOhm.
F Removal
Warning: isolate the boiler from the mains
electricity supply before removing any covering or
component.
1 Remove the cover (section 1.4).
2 Empty the main circuit (section 1.5)
3 Lower the control panel (section 1.7)
4 Disconnect the connector A (Fig. 18).
5 Unscrew and remove the temperature sensor.
6 Re-assemble the sensor following the removal
procedures in the reverse order.
Fig. 18
2.7. D.h.w. heat exchanger temperature sensor
The d.h.w. heat exchanger temperature sensor is placed
in the domestic cold water inlet pipe of the exchanger.
It has two functions:
1 when there is no d.h.w. draw off it senses the
temperature of the exchanger and operates the boiler in
order to keep the water at the desired temperature
(d.h.w. hold temperature).
2 when there is d.h.w. draw off it senses the temperature
change of the exchanger and operates the boiler in d.h.w.
mode.
F Removal
Warning: isolate the boiler from the mains
electricity supply before removing any covering or
component.
The sensor is not in direct contact with the water so it
isn’t necessary to empty the d.h.w. circuit.
1 Remove the cover (section 1.4)
2 Unscrew the screws A and move away the plate B (Fig.
19).
3 Disconnect the sensor from the control panel wiring.
4 Remove the holder spring C (Fig. 20) and extract the
sensor.
5 Re-assemble the sensor following the removal
procedures in the reverse order.
Fig. 20
Re-assembling the sensor use an adequate quantity of
thermal conductive grease and insert the sensor in the
jacket until it reaches the top.