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4. Installation
4.8.4 Lengths of the air/flue gas pipes
Type 2: Sealed combustion systems applications
Vertical or horizontal venting systems for both, the flue
gases and combustion air operating at two different
pressure zones or vent terminal locations.
Combustion air supply
Flue gas outlet
i
•
Flue gas vertical termination must be
tapered with a bird/rodent screen.
•
Horizontal breeching proportions shall be
kept to a minimum.
•
Horizontal sections of the venting must slope
downward towards the boiler ½" per linear
foot (42mm/m) and adequate vent support
must be provided.
•
Horizontal sections in the air supply must
slope away from the boiler towards the supply
opening and incorporate a drain connection if
the route rises from a lower point.
•
The maximum combined length L as seen in
the drawing can be found in the table.
Conventional chimney application with sealed air (two pipe system) and different pressure zones
Max.
Vent ø
MCA
length
Pro
in
mm
ft
35
3
80
131
45
3
80
131
*
65
3
80
108
65
4
100
131
90
4
100
131
115
4
100
131
Conventional chimney application with sealed air (two pipe system) and different pressure zones
Vent ø
Max. length
MCA
Pro
in
mm
ft
35
3
80
131
45
3
80
131
*
65
3
80
108
65
4
100
131
90
4
100
131
115
4
100
131
* with a 4" to 3" adaptor
46
Number of elbows 90˚ and equivalent feet/meters
1
2
m
ft
m
ft
m
40
118
36
105
32
40
118
36
105
32
33
95
29
82
25
40
115
35
99
30
40
115
35
99
30
40
115
35
99
30
1
2
m
ft
m
ft
40
127
39
123
40
127
39
123
33
104
32
100
40
127
39
122
40
127
39
122
40
127
39
122
Combustion
air supply
L = Maximum length
3
4
ft
m
ft
m
92
28
79
24
92
28
79
24
69
21
56
17
83
25
67
20
83
25
67
20
83
25
67
20
Number of elbows 45˚ and equivalent feet/meters
3
4
m
ft
m
ft
m
38
119
36
115
35
38
119
36
115
35
31
96
29
92
28
37
118
36
114
35
37
118
36
114
35
37
118
36
114
35
MCA Pro 45/65/90/115
Max. Length :
5
6
ft
m
ft
m
66
20
52
16
66
20
52
16
43
13
29
9
51
16
34
11
51
16
34
11
183
51
16
34
11
5
6
ft
m
ft
m
112
34
108
33
112
34
108
33
89
27
85
26
110
34
105
32
110
34
105
32
110
34
105
32
MCA-Pro ISM Rv.4.1 2/2017
Flue gas
outlet
7
8
ft
m
ft
m
39
12
26
8
39
12
26
8
16
5
3
1
18
6
2
1
6
2
1
18
6
2
1
7
8
ft
m
ft
m
104
32
100
30
104
32
100
30
81
25
77
23
101
31
97
30
101
31
97
30
101
31
97
30
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