IDEAL EVOMAX 30 Product Manual page 31

FLUE RESISTANCES
FLUE SYSTEMS
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.
PERMISSIBLE FLUE LENGTH
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.
TABLE 1
MAX PERMISSIBLE EQUIVALENT FLUE LENGTH
(INC TERMINAL RESISTANCE) METRES
CONCENTRIC
Flue Size 80/125 100/150
Model
30/30P 42 -
40/40P 52 -
60/60P 7.5 30
80/80P 12 35
100 - 14.3
120 - 17.6
150 - 7.5
MAX
PERMISSIBLE
MODEL FLUE TYPE EQUIVALENT
LENGTH
(TABLE 1)
60 80/125 7.5
60 100/150 30
80 80/125 12
120 100/150 17.6
TABLE 2
OPEN FLUE
Size
80 100
45˚
90˚
65 -
70 -
25 -
22 -
- 20
- 49
- 32
EXAMPLES OF FLUE LENGTH CALCULATION
EQUIVALENT
TYPE LENGTH
(TABLE 2)
90 1.6
90 1.9
90 1.6
90 1.9
EQUIVALENT LENGTH OF ELBOWS (METRES)
CONCENTRIC
80/125 100/150
0.85 1.25
1.6 1.9
ELBOWS
TOTAL
NO EQUIVALENT
LENGTH
2 3.2
2 3.8
3 4.8
4 7.6
OPEN FLUE
80 100
0.45 0.60
1.0 1.0
MAX
PERMISSABLE
STRAIGHT
LENGTH
4.3
26.2
7.2
10.0
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