Installation; Packaging; Handling; Boiler Room - Ferroli PREXTHERM RSW 92 Manual Técnico - Instalación - Uso Y Mantenimiento

5. INSTALLATION

5.1 Packaging

The PREXTHERM RSW boilers are supplied
complete with: door, smokebox and insulation
already installed, while the panels are contained
in a separate cardboard box.
The instrument panel and the layer of ceramic
fibre for the burner draught tube are placed insi-
de the combustion chamber.
Model 1250-3600 RSW boilers are supplied
complete with the insulation and casing.
The instrument panel is supplied in a card-
board box and positioned inside the combu-
stion chamber.

5.2 Handling

The PREXTHERM RSW boilers are fitted with
eyebolts for lifting. Make sure the hoisting equip-
ment used is suitable for the weight being lifted.
Before positioning the boiler, remove the woo-
den base support by unscrewing the fastening
screws (Fig. 5).
5.3 Boiler room (Fig. 6)
The PREXTHERM RSW boilers should be
installed in rooms exclusively used for this pur-
pose, in accordance with the technical stan-
dards and legislation in force and featuring ade-
quately sized ventilation openings.
The ventilation openings must be permanent,
directly communicating with the outside and
located in both a high and low position, in com-
pliance with the standards in force.
The location of the ventilation openings, the fuel
supply, power and lighting circuits must comply
with the legislation in force in relation to the type
of fuel used. To assist the cleaning of the flue gas
circuit, free space must be left at the front of the
boiler no less than the length of the boiler body
and, in any case, never less than 1300 mm,
checking that with the door open at 90° the distan-
ce between the door and the adjacent wall (X), is
at least equal to the length of the burner. The boi-
ler support surface must be perfectly horizontal. A
flat cement base should be used that is able to
support the overall weight of the boiler plus the
water content. For the dimensions of the base,
see the distances R x Q (table of dimensions). If
the burner is supplied with gas fuel whose specific
weight is higher than air, the electrical parts must
be located more than 500 mm from the floor. The
appliance cannot be installed outdoors as it is not
designed to operate outside and does not feature
automatic frost protection systems.
INSTALLATION IN OLD SYSTEMS
OR SYSTEMS TO BE UPGRADED
When the boiler is installed in old systems or
systems to be upgraded, check that:
- The flue stack is suitable for the temperature
of the products of combustion, calculated and
manufactured according to the standards in
force, airtight, insulated and not blocked or
choked.
- The electrical system has been installed in
compliance with the relevant standards by
qualified personnel.
- The fuel supply line and any tanks are made
according to the relevant standards.
- The expansion vessel/vessels can completely
absorb the expansion of the fluid contained in
the system.
- The flow-rate, discharge head and the direc-
tion of the flow of the circulating pumps are
suitable.
- The system is washed, cleaned of slime, fou-
ling, vented and watertight.
- A treatment system is available for special
supply/top-up water requirements (see the
reference values).

5.4 Discharge of the products of combustion

(Fig. 7)
The flue and the flue fitting must be made in
compliance with the standards and the legisla-
tion in force, using rigid pipes that are resistant
to high temperatures, condensate and mechani-
cal stress, and are airtight.
The flue must ensure the minimum negative
pressure specified by the standards in force,
considering "zero" pressure at the fitting to the
flue. Unsuitable or incorrectly sized flues may
increase the noise produced due to combustion,
generate problems involving condensation and
negatively affect the combustion parameters.
Non-insulated flues are a source of potential
danger. The joint seals should be made using
materials that can resist temperatures of at least
250°C. Suitable points for measuring the flue
gas temperature and analysing the products of
combustion must be prepared in the connection
between the boiler and the flue. As regards the
cross-section and the height of the chimney,
refer to the national and local standards in force.

5.5 Water connections

5.5.1 Supply water

The chemical characteristics of the supply and
top-up water are fundamental for the correct ope-
ration and the safety of the boiler. The water
should be treated using suitable systems.
The values shown in the table below can be used
as references.
TOTAL HARDNESS ppm
ALKALINITY mg/l CaCO
PH
SILICA ppm
CHLORIDES ppm
The water used in the central heating system
must be treated in the following cases:
- Very large systems
- Very hard water
- Frequent introduction of water to top up the
system.
If, in these cases, the system needs to be par-
tially or completely emptied, it must be refilled
with treated water. To control the volume of
water automatically refilled, an hour counter
should be installed. The most common pheno-
mena that occur in heating systems are:
- Lime scale deposits
Lime scale tends to concentrate at the points
where the temperature of the wall is higher.
Due to their low heat conductivity, lime scale
deposits cause a reduction in heat exchange
to the extent that even when just a few milli-
metres thick, the heat exchange between the
flue gas and the water is limited, bringing an
increase in the temperature of the parts expo-
sed to the flame and consequently breakages
(cracks) on the tube plate.
- 17 -
- Corrosion on the water side
Corrosion of the metal surfaces on the water
side of the boiler is due to the dissolution of
iron into its ions. The presence of dissolved
gases, in particular oxygen and carbonic
dioxide, play and important part in this pro-
cess. Softened and/or demineralised water
provides protection against lime scale and
other deposits, however does not protect
against corrosion. The water therefore must
be treated with corrosion inhibitors.

5.5.2 Central heating outlet/return pipes

The dimensions of the outlet and return pipes
are shown for each model of the boiler, in the
table of DIMENSIONS.
Check that the system features a sufficient num-
ber of vent openings. The boiler fittings must not
be stressed by the weight of the connection
pipes to the system, and consequently special
supports must be installed.

5.5.3 System fill/drain pipes

To fill and drain the boiler, a cock can be con-
nected to fitting T4 at the rear (see the drawing
of the DIMENSIONS).

5.5.4 Expansion vessel and safety valve pipes

The PREXTHERM RSW boilers are suitable for
operation with forced water circulation, both with
open and closed expansion vessels.
An expansion vessel is always required, to allow
for the increase in water volume due to heating.
In the first case, the height of the hydrostatic
column must be at least 3 metres above the boi-
ler casing and must have a sufficient capacity to
contain, between the surface of the water in the
vessel and the overflow pipe, the increase in
volume of all the water in the system.
High and narrow vessels are better, as they
ensure minimum contact between the water sur-
face and the air, thus reducing evaporation.
In the second case, the capacity of the closed
10 expansion vessel must be calculated considering:
750 - the total volume of water contained in the system
3
8÷9 - the maximum operating pressure of the system
100 - the maximum operating pressure of the
3500 expansion vessel
- the initial pre-charge pressure of the expan-
sion vessel
- the maximum operating temperature of the
boiler (the maximum temperature of the ther-
mostat fitted on the panel is 90°C; when
performing this calculation, use the value
100°C).
The expansion pipes connect the expansion
vessel to the system. This pipes that run from
fitting T3 (see the table of Dimensions), must
not be fitted with on-off valves. On fitting T3, or
on the outlet pipe, within 0.5 metres from the
first flange, install a safety valve sized for the
capacity of the boiler and in compliance with the
local standards in force. No type of shut-off devi-
ce may be installed between the boiler and the
expansion vessel, and between the boiler and
the safety valves, while the valves should cali-
brated for activation at values no higher than the
maximum admissible operating pressure.
GB