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36. Technical information, balanced flue
If a gas condensing boiler is installed with a balanced flue routed over an external wall
(type C13x), the rated output in heating mode must be reduced to below 11 kW (for
procedure, see chapter "Limiting the maximum heating output").
It must be possible to inspect the entire cross-section of the flues. Therefore, install
an appropriate cleaning and/or inspection port inside the boiler room; agree suitable
arrangements with your local flue gas inspector.
Flue connections are created using female connections and gaskets. Always arrange
female connections against the direction of the condensate flow.
Install the balanced
flue with a slope of at least 3° towards the gas condensing boiler. Install spacer
clips to secure the positioning (see installation examples).
Connection to the balanced flue
The calculated length of the balanced flue or standard flue is derived from the straight
pipe length and the length of any pipe bends.
Example for a 60/100 system
1)
:
Straight balanced flue, length 1.5 m
L = straight bend length
1 x 87° bend
≙
1.5 m
L = 1.5 m + 1 x 1.5 m + 2 x 1.3 m
2 x 45° bends
≙
2 x 1.3 m
L = 5.6 m
Calculating the balanced flue length
Note:
To avoid reciprocal interference between air and flue gas pipes routed above
the roof, we recommend maintaining a minimum clearance of 2.5 m between
the pipes.
1)
Equivalent length of the system:
60/100
80/125
87° bend
1.5 m
3 m
45° bend
1.3 m
1.5 m
Minimum duct size for room sealed operation C93x
Assuming: In the installation room:
2x inspection bends, 1x 87° bend and
1.5 m horizontal with 87° support bend
C93x
Flue DN 80
8
9
10
11
12
13
14
15
16
17
18
19
20
100
110
120
130
140
150
160
Square duct [mm]
Connection pipe
DN 60/100
Connection pipe
DN 80/125
Max. vertical length [m]
a
a
8
9
10
11
12
13
14
15
16
17
18
19
20
110
120
130
140
150
160
Connection pipe
DN 60/100
Connection pipe
DN 80/125
Round duct [mm]
Max. vertical length [m]
Flue DN 80
Ø
Max. duct length in [m]
Duct cross-section in [mm]
Connection pipe
DN 60/100
round
Connection pipe
DN 60/100
square
Flue DN 60