Installation Instructions Strebel Q-boiler range
19
6.7.1
Dimensioning of the flue gas and air intake duct
The flue diameter is determined by the total length of the run, including for the
connection pipe, elbows fittings and terminal covers etc and the type and number of
boilers installed into the system.
An undersized flue pipe can lead to disorders. Look at table 1 for the choice of the
system and the correct diameter. The table below shows the maximum flue lengths
with the different boiler outputs. A longer flue gas length can be achieved by increasing
the diameter to ø 100mm.
Explanation table 1:
Two pipe flue gas system:
maximum noted length = distance between boiler and roof
terminal A
Concentric flue gas system: maximum noted length = distance between boiler and
roof terminal B
When using bends the noted value behind every bend should be deducted from the
maximum straight length.
Pipes with 60/100 diameter are only permitted on wall terminals in
combination with STREBEL boilers untill 25kW.
ø80mm
A
in m
ø100mm
A
in m
16-25 kW
Maximum straight lenth 80
31 Maximum straight lenth 100
40
87° bend resistance length
-1,5
87° bend resistance length
-1,8
45° bend resistance length
-0,8
45° bend resistance length
-0,9
26-38 kW
Maximum straight lenth 80
18 Maximum straight lenth 100
39
87° bend resistance length
-1,5 87° bend resistance length
-1,8
45° bend resistance length
-0,8 45° bend resistance length
-0,9
39-60 kW
Maximum straight lenth 80
6
Maximum straight lenth 100
18
87° bend resistance length
-1,5 87° bend resistance length
-1,8
45° bend resistance length
-0,8 45° bend resistance length
-0,9
ø60/100mm
B
in m
ø80/125mm
B
in m
ø100/150mm
B
in m
16-25 kW
Maximum straight lenth 60/100
12 Maximum straight lenth 80/125
31 Maximum straight lenth 100/150
40
87° bend resistance length
-1
87° bend resistance length
-2,8 87° bend resistance length
-2,6
45° bend resistance length
-1
45° bend resistance length
-1,1 45° bend resistance length
-1,1
26-38 kW
Maximum straight lenth 80/125
13 Maximum straight lenth 100/150
34
87° bend resistance length
-2,8 87° bend resistance length
-2,6
45° bend resistance length
-1,1 45° bend resistance length
-1,1
39-60 kW
Maximum straight lenth 80/125
6
Maximum straight lenth 100/150
10
87° bend resistance length
-2,8 87° bend resistance length
-2,6
45° bend resistance length
-1,1 45° bend resistance length
-1,1
Concentric flue system
Two pipe flue chimney lining
Dimensions flue gas system and air supply system
Table 5
Example:
A 25kW with a
concentric flue gas system
ø80/125mm has according to
the table a maximum flue
straight length of 31m In the
system that is going to be put in
there are 2 x 45° bends, so the
maximum flue gas length is
40 – ( 2 x 1.1 ) = 37.8 meters.
