Primary Heat Exchanger; Characteristics; Removal; Cleaning - Biasi GARDA M90F.24S Service Manual

5

Primary heat exchanger

5.1

Characteristics

The primary heat exchanger A in Fig. 9 has the function
of transferring heat produced from combustion of the
gas to the water circulating in it.
Fig. 9
The hydraulic circuit is composed of 8 elliptical pipes
connected in parallel (Fig. 10).
Fig. 10
5.2

Removal

Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1 Empty the primary circuit of the boiler.
2 Remove the case panels and the sealed chamber
lid (see section 2).
Remove the combustion chamber lid B by un-
3
screwing the screws C (Fig. 11).
3b For model M90F.28S, M90F.28SR and M90F.32S
only, remove the screw D and the plate E.
4 Remove the clips F and the safety thermostat G.
It is not necessary to disconnect it from the wiring.
10
A
C
B
Fig. 11
Unscrew the connection H (Fig. 12), lift the pipe
5
I and rotate it right then move it downwards free-
ing it from the heat exchanger connection.
6 Remove the motor of the three way diverter valve
(see section 8.3).
7 Completely unscrew the connection J and rotate
the pipe K downwards freeing it from the heat ex-
changer connection.
8 Remove the heat exchanger by sliding it for-
wards.
9 Reassemble the boiler carrying out the removal
operations in reverse order. Fit the clips F with
the arrow pointing upwards as illustrated in
Fig. 11.
J
K
Fig. 12
5.3

Cleaning

If there are deposits of soot or dirt between the blades
of the heat exchanger, clean with a brush or non---me-
tallic bristle brush.
In any case, avoid any actions that can damage the pro-
tective varnish with which the exchanger has been cov-
ered.
Warning: After cleaning or replacement as
detailed above refer to section Combustion
analysis check in the chapter Maintenance of
the installation instructions manual.
G
F
E
D
I
H