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6.5.2 Single & Cascade resistance tables of air inlet and flue.
The output of the boiler is affected by the resistance of the air inlet and flue system (as a result of controlled
gas/air ratios in the Boiler). At a resistance up to 250 Pa, the output will be as indicated on the Boiler data
plate
.
Higher resistance of up to
600 Pa max
can be overcome with reduced Boiler output (see page 12).
An under pressure, in the flue gas outlet, is not required, a positive pressure is created by the fan of the Boiler
which is specially designed for this purpose. As a result of this, the diameter of the common air inlet and flue
gas outlet is minimised; while the built in non return air valve prevents recirculation between the Boilers
when 2 or more are used on a common flue.
Table Resistance of the air inlet system
The stated Air inlet diameter is that used between the boilers and the roof or wall terminal.
Transmission
kW
80 mm
Pa/m
100 mm
Pa/m
130 mm
Pa/m
150 mm
Pa/m
180 mm
Pa/m
200 mm
Pa/m
250 mm
Pa/m
60 4
1
0.35
90 7
2
0.6
120 10
4 1 0,4
150 15
6 1,5
0,6
180 24
9 2 1
0,5
210 12
2,5
1,4
0,6
240 15
3 1,8
0,7
270 18
4 2,2
0,8
300 21
5 2,6
0,9
330 25
7 3
1,1
0,8
360 8 3,4
1,3
0,9
390 9 3,8
1,5
1
420 10,5
5,3
1,7
1,2
450 12
5,8
2
1,3
480 13
6,3
2,3
1,4
510 14
6,5
2,6
1,5
540 15
7
2,9
1,8
570 16
8
3,3
2,1
600 18
9
3,6
2,3
0,65
630 20
10
3,9
2,4
0,7
660 22
11
4,2
2,5
0,75
690 23
12
4,6
2,6
0,8
720 25
13
5
3
0,85
750 27
14
5,4
3,5
0,90
780 28
15
5,8
4
0,95
810 30
16
6,2
4,2
1
840 17
6,6
4,3
1,1
870 18
7,0
4,3
1,2
900 20
7,5
4,5
1,3
930 21
8
4,7
1,4
960 22
8,5
4,9
1,6
990 23
9,0
5,2
1,8
1020
25
9,5
5,5
2
Resistance of the different parts of the inlet system: Standard Flue pipe can be used for the air inlet.
*Bend 90° : equal to 1 meter straight tube of the same diameter.
*Bend 45° : equal to 0,5 meter straight tube of the same diameter.
*Cascade T-piece on top of the boiler equal to 1 meter straight tube.
*Parallel Roof & wall terminal air inlet resistance is equal to 1 meter straight length of same size.
* See sample calculation page 16.
Install horizontal Flue parts under 1% fall in the direction of the boiler (one centimetre for every
linear metre)
.
