24
For concentric flue systems with elbows fitted, use the table to correct the maximum flue extension capability.
Alternatively use the table to design the flue system, deducting the individual resistance of components from
the maximum pressure drop allowed in the flue for that boiler. The maximum pressure drop allowed in the flue is
given below.
The maximum permissible flue lengths for each model are shown in Table 1 below, these lengths are inclusive of
the terminal resistance. The value shown is the maximum available length for extension. The equivalent length of
elbows is shown in Table 2.
FLUE RESISTANCES
FLUE SYSTEMS
TABLE 1
TABLE 2
MAX PERMISSIBLE EQUIVALENT FLUE LENGTH
(INC TERMINAL RESISTANCE)
METRES
CONCENTRIC
OPEN FLUE
Flue Size 80/125
100/150
80
100
Model
30/30P
33
-
65
-
40/40P
30
-
70
-
60/60P
17.5
28
25
-
80/80P
10
18
15.3
-
100
-
10
-
20
120
-
9
-
49
150
-
6
-
32
EQUIVALENT LENGTH OF ELBOWS
(METRES)
CONCENTRIC
OPEN FLUE
Size
80/125
100/150
80
100
45˚
0.85
1.25
0.45
0.60
90˚
1.6
1.9
1.0
1.0
EXAMPLES OF FLUE LENGTH CALCULATION
MODEL
FLUE TYPE
MAX
PERMISSIBLE
EQUIVALENT
LENGTH
(TABLE 1)
ELBOWS
MAX
PERMISSIBLE
STRAIGHT
LENGTH
TYPE
EQUIVALENT
LENGTH
(TABLE 2)
NO
TOTAL
EQUIVALENT
LENGTH
60
80/125
17.5
90
1.6
2
3.2
14.3
60
100/150
28
90
1.9
2
3.8
24.2
80
80/125
10
90
1.6
3
4.8
5.2
120
100/150
9
90
1.9
4
7.6
1.4
PERMISSIBLE FLUE LENGTH
Summary of Contents for EVOMAX 2 30
Page 1: ...EVOMAX 2 CONDENSING BOILER PRODUCT FLUE GUIDE...
Page 5: ...5...
Page 12: ...12 EVOMAX 2 CASCADE 30 900kW...
Page 18: ...18 EVOMAX 2 FLUE OPTIONS...
Page 19: ...19...
Page 41: ...41...
Page 43: ...43 NOTES...
