2.3. 1
Filter on the gas pipe
The gas valve is supplied ex factory with an
inlet filter, which, however, is not adequate to
entrap all the impurities in the gas or in gas
main pipes. To prevent malfunctioning of the
valve, or in certain cases even to cut out the
safety device with which the valve is equip-
ped, install an adequate filter on the gas pipe.
2.4
CHARACTERISTICS
OF FEEDWATER
To prevent lime scale and damage to the
tap water exchanger, the water supplied
should have a hardness of no more than
20°F. In all cases the water used should be
tested and adequate treatment devices
should be installed. To prevent lime scale or
deposits on the primary exchanger, the
water used to supply the heating circuit
should must be treated in accordance with
UNI-CTI 8065 standards. It is absolutely
essential that the water is to be treated in
the following cases:
– very extensive system (with high con-
tents of feedwater);
– frequent addition of makeup water into
the system;
– should it be necessary to empty the
system either partially or totally.
2.5
SYSTEM FILLING
The filling of the boiler and of the system is
carried out by pressing the filling cock loca-
ted on the bottom of the boiler (fig. 7).
The filling pressure of the system cold must
be 1 bar. Once the filling has been comple-
ted, close the filling cock.
CLOSE
2.6
FLOW REGULATOR (fig. 7/a)
At the inlet of the hot water a flow regulator
can be installed, from 10 l/min (yellow) for
the "25/60" version and from 12 l/ min
(brown) for the "30/60" version; the regu-
lator is supplied in the kit of the connecting
taps code 8091805.
2.7
FLUE
The flue for the atmospherical expulsion of
the combustion products from natural
draught appliances must meet the following
requirements:
– Be gas-tight to the combustion products,
waterproof and thermally insulated.
– Be built of materials suitable for keep
resisting to normal mechanical stresses,
heat, and the action of combustion pro-
ducts and their possible condensates.
– Follow a vertical path and not present
any throttling throughout its entire
length.
– Be adequately insulated to prevent phe-
nomena of condensation or smokes coo-
ling, in particular if located outside the
building or in unheated ambiences.
– Be set at an adequate distance from
combustible or easily inflammable mate-
rial by means of an air gap or suitable
insulating material.
– Have beneath the mouth of the first
smoke duct a chamber for collecting
solid material and any condensate; the
height of the chamber must be at least
500 mm.
Access to the chamber must be guaran-
teed by means of an opening provided
with an air-tight metal door.
– Have a circular, square, or rectangular
internal cross section; in the case of
square or rectangular sections, the cor-
ners must be rounded off with a radius
of no t less t han 20 mm. However,
hydraulically equivalent cross sections
are allowed.
– Be equipped with a chimney-pot at the
top, which must be outside the so-called
back-flow zone, so as to prevent the for-
mation of back-flow, which prevents free
discharge of the products of combustion
Fig. 7
into the atmosphere.
– Be devoid of mechanical means of suc-
tion located at the top of the pipe.
– No overpressure should be present in a
chimney that passes within or close up
to inhabited rooms.
2.7. 1
Connecting up flue
Fig. 8 refers to the connection of the boiler
"25/60 OF" to the flue or chimney throu-
gh smoke ducts. When making the con-
nection, in addition to respecting the
dimensions given, you are recommended
to use gas-tight materials capable of resi-
sting over time mechanical stresses and
the smokes heat.
At any point along the smoke duct, the tem-
perature of the combustion products must
be higher than the dew point. More than a
total of three changes of direction must not
be made, including the inlet connection to
the chimney/flue. For any changes of direc-
tion use only curved pipe lengths.
Fig. 7/a
Fig. 8/a shows some applications of drau-
ght terminals that ensure proper expulsion
of the combustion products, in case of
discharge through the wall.
Fig. 8
Fig. 8/a
77