tank must correspond to, and in no case
be less than, the height of the static
column of the heating system (for exam-
ple, in the case of a static column of 5
metres, tank pre-filling pressure and fil-
ling pressure must at least correspond
to a minimum of 0.5 bar).
2.5
FLUE
Combustion waste of natural draught boi-
lers: The flue for evacuation into the envi-
ronment must meet the following requi-
rements:
– be sealed against products of combu-
stion, waterproof and heat insulated;
– made of materials which can resist
normal mechanical stress, heat and
the action of products of combustion
and condensation produced by them
over time;
– vertically oriented and free of choking
throughout its length;
– adequately insulated to prevent con-
densation or the cooling of flue gases,
especially if located outside the buil-
ding or in unheated premises;
– separated from combustible or highly
flammable materials by an air space
or appropriate insulation;
– provided with a chamber at least 500
mm high for collection of solid mate-
rials and condensation underneath
the entrance of the first channel. This
chamber must be accessible through
an opening with a metal door which
does not let air in;
– circular, square or rectangular inter-
nal section; if square or rectangular,
corners must be rounded off with a
radium of no less than 20 mm;
hydraulically equivalent sections are
also permitted;
– fitted with a chimney at the top, the
outlet of which must be outside the
so-called reflux area to prevent for-
mation of counter-pressure preven-
ting the products of combustion from
being freely released into the environ-
ment.
It is thus, necessary to comply with
the minimum heights shown in fig. 4 ;
– without mechanical intake devices at
the top of the flue;
– if the flue passes through or is adja-
cent to inhabited rooms, there must
be no over-pressure.
2.5.1
Flue size
The correct sizing of the flue is an essen-
tial condition for efficient boiler operation.
The main factors to be taken into consi-
deration for calculating the section are
the heat input of the boiler, the type of
fuel, the percentage of CO
2
, the mass
flow of smoke at a nominal load,
the temperature of the smoke, the rou-
ghness of the internal wall, and the effect
of gravity on the draught pressure, which
must take into account the external tem-
perature and the altitude.
2.6
CONNECTING THE BOILER
The boiler is provided with an electric
wire which, in the case of replacement,
has to be ordered from SIME.
27
IT
GB
FR
BE
DE
Tetto piano
0,50 m
0,50 m
Volume
tecnico
> 5 m
≤
5 m
Colmo
> 1,50 m
≤
1,50 m
Zona di reflusso
1
,50 m
2 m min.
0,50 m
oltr
e il colmo
45
°
Tetto a 45
°
Colmo
> 1,30 m
≤
1,30 m
Zona di reflusso
0,80 m
1
,20 m min.
0,50 m
oltr
e il colmo
30
°
Tetto a 30
°
Fig. 4
Flat roof
30° roof
45° roof
