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9.0 Plume Displacement
26
© Baxi Heating UK Ltd 2011
1
0
2
4
6
8
10
12
14
70Ø Exhaust (metres)
Concentric 70/110 Flue (metres)
0
16
18
234
20
30
22
24
26
28
30
1
0
2
4
6
8
10
12
14
70Ø Exhaust (metres)
Concentric 70/110 Flue (metres)
0
16
18
234
20
30
22
24
26
28
30
1
0
2
4
6
8
10
12
14
70Ø Exhaust (metres)
Concentric 70/110 Flue (metres)
0
16
18
234
20
30
22
24
26
28
30
Flue Length - Worked Example
In Fig. D opposite an additional 93° elbow and pair of 45°
elbows have been included in the 70Ø exhaust.
Also 3 straight extension pieces have been used.
To calculate total length:-
Length of 70Ø supplied in kit = 1 metre
3 x 1 metre Extensions = 3 metres
1 x 93° Elbow = 1 metre
2 x 45° Elbow = 1 metre (0.5 metres each)
Total 70Ø = 6 metres
After consulting the table in Example 3 it can be determined
that the concentric flue could be up to approximately 3.25
metres long.
Concentric Flue
Support
Bracket
45° Elbow
93° Elbow
1 metre Extension
1 metre supplied in kit
Additional Accessories
A - 93° Elbow 5117381
B - 45° Elbow (Pair) 5117382
C - 1 metre 60Ø Extension 5117380
9.2 Determining Permissible Lengths - P.D.K.
In the graph the solid line diagonal represents the
relationship between the concentric flue assembly (and any
extensions) and the 70Ø exhaust (and any extensions or
additional bends).
Example 1 - Not Permissible
If, for instance, a concentric length of 3.25 metres was
required and the 70Ø exhaust needed to be 10 metres the
graph shows that this combination would NOT be
permissible as the intersection point would be above the
solid diagonal line.
Example 2 - Flue Lengths OK
Where both lengths have been determined they can be
applied to the graph to check that the installation is
permissible. For example, if it was known that 2 metres of
concentric flue and 4 metres of 70Ø exhaust were required,
the values could be applied to the graph as shown in
Example 2.. As the point of intersection of the dotted lines is
below the solid diagonal line, the combination of lengths is
shown to be acceptable.
Example 3 - Flue Lengths OK
In the example shown, assume that the concentric part of
the flue needs to be 2 metres long. Find the position of ‘2’ on
the horizontal axis of the graph and then project upwards to
the solid diagonal line. This is represented by the vertical
thick dotted line. Where this dotted line intersects with the
solid diagonal line on the graph, project across to the vertical
axis. As can be seen this corresponds with 14 metres.
Therefore, the total equivalent length of the 70Ø exhaust
can be up to 14 metres. Any elbow equivalencies must be
accounted for i.e. 93° elbows are equal to 1 metre, each 45°
elbow to 0.5 metres.
Example 1
Flue Lengths - Not Permissible
Example 2
Flue Lengths - OK
Example 3
Flue Lengths - OK
Concentric 70/110 Flue
(MUST be installed
horizontally)
70Ø Exhaust
X
Y
Fig. D