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fAN AND AIR Box
17 fAN AND AIR Box
17.1 function
The function of the Fan A (Figure 17.1) is to force the mixture of
air and gas into the burner.
The function of the Air box B is to mix the gas and the air in the
right proportion.
The flow rate of the air-gas mixture and consequently the input
power of the boiler is proportional to the speed of the fan that is
controlled by the electronic control p.c.b.
figure 17.1
A
B
17.2 Removal of the Air box and the fan
Warning: isolate the boiler from the mains electrici-
ty supply before removing any covering or compo-
nent.
1 Turn off the gas supply.
2 Remove all the case panels and the sealed chamber lid (see
section "General access and emptying hydraulic circuits"
page 5).
figure 17.2
C
D
E
f
3 Disconnect the air manifold C (Figure 17.2) by pulling it.
figure 17.3
Fan gasket
G
H
I
J
k
L
4 Disconnect the rubber pipe G (Figure 17.3).
figure 17.4
M
5 Unscrew the gas connector M (Figure 17.4)
6 Remove the fixing fork H and remove the gas pipe I (Figure
17.3).
7 Loosen without removing the screw J.
8 Remove the screws K and the air box L. Leave the air box
with the air manifold clamped to the water pipe.
9 Disconnect the fan connector K by pressing the plastic hook
placed on the side of the connector (Figure 17.2).
10 Unscrew the screws D (Figure 17.2).
11 Remove the fan E.
12 Assemble the Fan and the Air box carrying out the removal
operations in reverse sequence.
Before reassembling ensure the fan gasket (figure 17.3) is
correctly mounted.
Warning: After cleaning or replacement as detailed
above, it is deemed necessary to undertake a com-
bustion analysis as detailed in section "Adjust-
ment" page 25.
