36
20
Flue temperature probe NTC
20.1
Function
The Flue temperature probe NTC
A
in Fig. 80 and
Fig. 81 senses the temperature of the combustion
products that flow through the condensing heat ex-
changer.
A
Fig. 80
If the temperature of the combustion products circuit
reaches the limit temperature, the Flue temperature
probe NTC reduces the gas flow rate to the burner. The
temperature of the combustion products should de-
crease to a safe value temperature.
In the case that the temperature of the combustion
products reaches a potentially dangerous value, it
stops the boiler operation. It is therefore allowed the
use of plastic materials for the flue outlet pipes and
bends.
The use of kits different from the original isn’t how-
ever allowed, since the flue pipes are integral parts
of the boiler.
If not, the electronic control p.c.b. attempts to light the
burner and, at the end, locks the boiler and lights the
lock---out signal lamp.
B
Fig. 81
20.2
Checks
n
Overheat temperature value
1
Set the temperature control knobs to their max.
position and run the boiler in d.h.w. and c.h.
2
Allow the boiler to reach its maximum operating
temperature (monitor the temperature gauge on
the instrument panel). The boiler should maintain
a temperature below that of the Flue temperature
probe NTC and no overheat intervention should
occur.
20.3
Removal
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1
Remove all the case panels and the sealed
chamber lid.
2
Disconnect the wires from the Flue temperature
probe NTC.
3
Unscrew and remove the thermostat probe
B
(Fig. 81) from the condensing heat exchanger.
4
Assemble the Flue temperature probe NTC carry-
ing out the removal operations in reverse se-
quence.
