Atag Q 25S - Dimensions of the Flue Gas and Air Intake Duct

Installation & Servicing Instructions ATAG Q-Series
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6.8.1 Dimensioning of the ue gas and air intake duct
The ue diameter is determined by the total length of the run, including for the connection
pipe, elbows ttings and terminal covers etc and the type and number of boilers installed
into the system.
An undersized ue pipe can lead to disorders. Look at table 6.8.1.a for the choice of the
system and the correct diameter. The table below shows the maximum ue lengths with
the different boiler outputs. A longer ue gas length can be achieved by increasing the
diameter to ø 100mm.
Explanation table 6.8.1.a:
Two pipe ue gas system: maximum noted length = distance between boiler and roof
terminal A
Concentric ue 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.
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 -1,4 87° bend resistance length -2,1
45° bend resistance length -0,9 45° bend resistance length -2
26-38 kW Maximum straight lenth 80 18 Maximum straight lenth 100 39
87° bend resistance length -1,4 87° bend resistance length -2,1
45° bend resistance length -0,9 45° bend resistance length -2
39-60 kW Maximum straight lenth 80 6 Maximum straight lenth 100 18
87° bend resistance length -1,4 87° bend resistance length -2,1
45° bend resistance length -0,9 45° bend resistance length -2
ø60/100mm
B
in m
ø80/125mm
B
in m
ø100/150mm
B
in m
16-25 kW Maximum straight lenth 80/125 31 Maximum straight lenth 100/150 40
87° bend resistance length -3 87° bend resistance length -1,7
45° bend resistance length -1,9 45° bend resistance length -1,3
26-38 kW Maximum straight lenth 80/125 13 Maximum straight lenth 100/150 34
87° bend resistance length -3 87° bend resistance length -1,7
45° bend resistance length -1,9 45° bend resistance length -1,3
39-60 kW Maximum straight lenth 80/125 6 Maximum straight lenth 100/150 10
87° bend resistance length -3 87° bend resistance length -1,7
45° bend resistance length -1,1 45° bend resistance length -1,3
Concentric flue system
Two pipe flue system + chimney lining
Dimensions ue gas system and air supply system Table 6.8.1.a
Example:
A 25kW with a concentric
ue gas system ø80/125mm
has according to the table a
maximum ue straight length
of 31m In the system that is
going to be put in there are 2
x 45° bends, so the maximum
ue gas length is
31 – ( 2 x 1.9 ) = 27.2 meters.