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Heating engineer
24
3
Incorrect positioning of the gasket G can compro-
mise the correct discharge of the flue gas outside
and consequently damage the appliance.
Figure 3.5
Correct gasket positioning
G Gasket
G
3.4.3
Possible flue
If required, the appliance may be connected to a flue ap-
propriate for condensing appliances.
▶
To size the flue refer to Table 3.4
manual.
▶
Use ducts and terminals suitable for forced draft con-
densing appliances.
▶
If several appliances are connected to a single flue, it
is obligatory to install a check valve on the flue gas ex-
haust of each.
▶
The flue must be designed, sized, tested and con-
structed by a skilled firm, with materials and compo-
nents complying with the regulations in force in the
country of installation.
▶
Always provide a socket for flue gas analysis, in an ac-
cessible position.
▶
The horizontal sections for flue gas exhaust must al-
ways be mounted on a slope towards the appliance (3°
slope = 5 mm per metre of pipe).
▶
For vertical ducts longer than 1,5 m, a curve and a
Tee (Figure 3.6
p. 24) for condensate collection and
drainage must be provided. The condensate must
then be evacuated in accordance with the regulations
in force, at the same time as that coming from inside
the boiler.
In case the check valves are installed outside, an
appropriate UV ray protection must be assured (if
the valve is in plastic) as well as protection from
potential winter freezing of condensate backflow
into the siphon.
The connection of the discharge to the sewerage
system must be made at atmospheric pressure, i.e.
by dripping into a siphoned container connected
to the sewerage system.
Figure 3.6
Flue gas condensate drain
> 300 mm
3.4.3.1
Maximum exhaust pipe length
Table 3.4
Characteristics of flue gas exhaust
AY 35
AY 50
AY 100
Installation data
Flue gas
exhaust
residual
head
Pa
91
100
100 (1)
diameter (Ø) mm
80
80 (2)
maximum equivalent length
of exhaust duct
m
15
14
14 (1)
(1) For each of the independent flue gas exhausts.
(2) 2 independent flue gas exhausts.
The maximum exhaust length (or equivalent linear length)
is obtained by adding the length of the linear duct to the
equivalent length of each additional curve.
The equivalent lengths of linear ducts and curves are giv-
en in Table 3.5
Table 3.5
Pressure drop of flue pipes
Equivalent
length (m)
Pressure
drop (Pa)
AY 35
extension pipe Ø 80 mm, length 1000
mm
1
5,8
elbow 90° Ø 80 mm
1,5
8,7
elbow 45° Ø 80 mm
1,2
7,0
T connector Ø 80 mm
3
17,4
AY 50/AY 100
extension pipe Ø 80 mm, length 1000
mm
1
7,0
elbow 90° Ø 80 mm
2,5
17,5
elbow 45° Ø 80 mm
1,4
7,8
T connector Ø 80 mm
3
21,0
3.5
FLUE GAS CONDENSATE DRAIN
The provided condensate drain hose must be connected
to a suitable collection and disposal system in accordance
with the applicable regulations in force.