Recirculating Pump; Opening And Adjusting The Front Door; Assembling The Burner; Connecting The Flame Inspection Window - Ferroli PREXTHERM RS3 Mode D'emploi

5.5.5 Recirculating pump (Fig. 7)
The condensation of the water vapour contained
in the flue gas leaving the boiler (condensate)
occurs when the return water temperature is
less than 55°C and is significant above all when
starting in the morning, after the boiler has been
off all night. This condensate is acidic and corro-
sive and, over time, attacks the metal plate on
the boiler. Consequently, a recirculating pump
with the function of preventing condensate
should be installed between the outlet and
return fittings, upstream of any mixing valve.
The pump must ensure, when the system is
operating, a flow-rate of between 20 and 30% of
the total; it must also ensure a return water tem-
perature no less than 55°C, while the required
discharge head is quite low, as it only needs to
overcome the resistance of the boiler and the
valves. To measure the effective central heating
return inlet temperature for the purpose of con-
trolling the condensate prevention pump or
managing the functions for getting the system to
stable temperature operation, a probe socket
must be fitted at a distance equivalent to 3-5
times the diameter of the return pipe upstream
of the water coupling.

5.6 Opening and adjusting the front door

For PREXTHERM RS3 models the door is hin-
ged, fastened and reversed as regards the
direction of opening as shown in Fig. 8. The fol-
lowing operations are required:
- The door is supplied with four equal brackets
(pos. 3) and hinges.
- To establish the direction of opening, RIGHT
or LEFT, unscrew the nut (pos. 7), unscrew
and remove the R or L nut (pos. 6), depen-
ding on which side the door opens from.
- Height adjustment of the door is performed
using the nut (pos. 2); after having completed
the adjustments tighten the dowels (pos. 1).
- Longitudinal adjustment is performed using
the screw (pos. 8).
Key (Fig. 8)
1 Fastening dowel
2 Door support/adjustment nut
3 Hinge bracket
4 Hinge pin
5 Hinge screw
6 Hinge fastening nut
7 Fastening nut
8 Hinge bracket fastening/adjustment screws
and nuts
5.7 Assembling the burner (Fig. 11)
The assembly of the burner to the door of the
boiler must ensure perfect tightness to the pro-
ducts of combustion.
Once having installed the burner on the boiler,
the space between the burner draught tube and
the refractory material on the door must be filled
with the layer of ceramic fibre (A) supplied.
This prevents the door from overheating and
consequently from being irreversibly deformed.
The fuel connections to the burner must be loca-
ted so as to allow the complete opening of the
boiler door with the burner installed.
PREXTHERM RS3 L min. (mm)
70-152 230
190-240 250
320-399 290
500-600 320
720-820 320
940-1060 340
1250-1480 340
1890-2360 350

5.8 Connecting the flame inspection window

(Fig. 10)
The flame inspection window features a pressu-
re fitting (1) to be connected via a silicone hose
or copper pipe to the outlet on the burner (2).
This operation allows the air blown by the fan to
cool the glass and prevent it from turning black.
Failure to connect the hose or pipe to the win-
dow may cause the glass to break.
5.9 Assembling the panels, models 92-190
Assembly sequence (Fig. 11)
a) Position the right and left side panels (pos. 1-
2) hooking them to the support (pos. 13).
To know which of the two sides is the right or
the left, refer to the hole for the cable gland
plate (pos. 6), which must be facing the front
of the boiler.
b) Fasten the control panel to the top panel
(pos. 3).
c) Rest the top right panel (pos. 3), complete
with the control panel, to the side panel (pos.
1) complete with springs, closing pins and
nuts (pos. 10-11-12).
d) Insert the bulbs of the instruments into the
sheaths as shown in Fig. 20 and make the
electrical connection between the control
panel and the power line, burner and any
pumps etc. The probes should be inserted
fully into the corresponding sockets, to impro-
ve contact. Then secure the capillary tubes
with the springs. Close the cover on the elec-
trical panel, pass the burner plug through the
side plate (pos. 6) and secure the cable with
the cable gland supplied. Fasten the plate
(pos. 6) with the screws (pos. 7).
e) Fit the panel left top (pos. 4) to the left side
panel (pos. 2) complete with springs, closing
pins and nuts (pos. 10-11-12).
f) Fit the rear panel (pos. 8) to the boiler using the
screws (pos. 13).
g) Fasten the rating label to the boiler, see
Chap. 1, after having cleaned and degreased
the part in question using a suitable solvent,
and apply it so as to ensure perfect adhesion.
Do not remove the rating label, as it will lose
its adhesiveness.
- 18 -
L max. (mm) The rating label is included in the document
300 envelope.
320
360 5.10 Assembling the panels, models 240-2360
Assembly sequence (Fig. 12)
390
390 a) Position the side panels (pos. 1-2 and 3-4)
410 hooking them to the supports (pos. 19).
470 b) Position the top right panel (pos. 5-6) and
480 then the left panel (7-8) hooking them to the
supports on the boiler (pos. 19) and to the
crossbeam (pos. 15).
c) Fasten the control panel to the top right panel
(pos. 5).
d) Rest the top panel (pos. 5), complete with the
control panel, to the side panel (pos. 1) com-
plete with springs, closing pins and nuts (pos.
12-13-14).
e) Insert the bulbs of the instruments into the sheats
as shown in Fig. 21 and make the electrical
connection between the control panel and the
power line, burner and any pumps etc. The pro-
bes should be inserted fully into the correspon-
ding sockets, to improve contact. Then secure
the capillary tubes with the springs. Close the
cover on the electrical panel, pass the burner
plug through the side plate (pos. 10) and secure
the cable with the cable gland supplied. Fasten
the plate (pos. 10) with the screws (pos. 11).
f) Fit the support (pos. 15).
g) Fit the top panels (pos. 5-6-7-8) hooking them
to the side panels (pos. 1-2-3-4) complete
with springs, closing pins and nuts (12-13-14).
h) Fasten the rating label to the boiler, see
Chap. 1, after having cleaned and degreased
the part in question using a suitable solvent,
and apply it so as to ensure perfect adhesion.
Do not remove the rating label, as it will lose
its adhesiveness.
The rating label is included in the document
envelope.