INSTALLATION CONSIDERATIONS
22
*MSS9* / *CSS9 Direct Vent (2-Pipe) & Non-Direct Vent (1-Pipe)
(6)
Maximum Allowable Length of Vent/FLue Pipe
MODEL
PIPE
SIZE
1
2
3
4
5
6
7
8
2
165
160
155
150
145
140
135
130
3
168
161
154
147
140
133
126
119
2
55
50
45
40
35
30
25
20
3
127
120
113
106
99
92
85
78
2
30
25
20
15
10
5
N/A
N/A
3
72
65
58
51
44
37
30
23
2
30
25
20
15
10
5
N/A
N/A
3
72
65
58
51
44
37
30
23
2
40
35
30
25
20
15
10
5
3
72
65
58
51
44
37
30
23
2
60
55
50
45
40
35
30
25
3
168
161
154
147
140
133
126
119
2
30
25
20
15
10
5
N/A
N/A
3
113
106
99
92
85
78
71
64
2
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
3
65
58
51
44
37
30
23
16
2
100
95
90
85
80
75
70
65
3
137
130
123
116
109
102
95
88
2
60
55
50
45
40
35
30
25
3
127
120
113
106
99
92
85
78
2
35
30
25
20
15
10
5
N/A
3
160
153
146
139
132
125
118
111
2
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
3
127
120
113
106
99
92
85
78
MODEL
PIPE
SIZE
1
2
3
4
5
6
7
8
2
100
95
90
85
80
75
70
65
3
168
161
154
147
140
133
126
119
2
45
40
35
30
25
20
15
10
3
168
161
154
147
140
133
126
119
2
35
30
25
20
15
10
5
N/A
3
168
161
154
147
140
133
126
119
2
60
55
50
45
40
35
30
25
3
113
106
99
92
85
78
71
64
2
45
40
35
30
25
20
15
10
3
120
113
106
99
92
85
78
71
2
40
35
30
25
20
15
10
5
3
151
144
137
130
123
116
109
102
2
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
3
158
151
144
137
130
123
116
109
2
100
95
90
85
80
75
70
65
3
137
130
123
116
109
102
95
88
2
45
40
35
30
25
20
15
10
3
168
161
154
147
140
133
126
119
2
40
35
30
25
20
15
10
5
3
120
113
106
99
92
85
78
71
2
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
3
113
106
99
92
85
78
71
64
2
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
3
110
103
96
89
82
75
68
61
*MSS960803BN
*MSS960804BN
*MSS960805CN
*MSS961005CN
*CSS961005CN
*CSS961205DN
*MSS961205DN
*CSS960402BN
*CSS960603BN
*CSS960804CN
*CSS920402BN
*CSS920603BN
*CSS920804CN
*CSS921005CN
*MSS960402BN
Number of Elbows
(3) (5)
*MSS920402BN
*MSS920603BN
*MSS960603BN
*MSS920803BN
*MSS920804CN
*MSS920805CN
*MSS921004CN
*MSS921005CN
*MSS921205DN
1)
Maximum allowable limits listed on individual lengths for inlet and flue and
NOT a combination.
2)
Minimum requirement for each vent pipe is five (5) feet in length and one
elbow/tee.
3)
Tee used in the vent/flue termination must be included when determining
the number of elbows in the piping system.
4)
2 1/2” or 3” diameter pipe can be used in place of 2” diameter pipe.
5)
Increased Clearance Configurations using (2) 45 deg. Long Sweep elbows
should be considered equivalent to one 90 deg. elbow.
6)
One 90° elbow should be secured to the combustion air intake connection.
Vent/Flue and Combustion Air Pipe Lengths and Diam-
eters
Refer to the preceding table for applicable length, elbows,
and pipe diameter for construction of the vent/flue and com-
bustion air intake pipe systems of a non-direct vent (single
pipe) installation. The number of elbows tabulated repre-
sents the number of elbows and/or tees in each (Vent/Flue
& Combustion Air Intake) pipe. Elbows and/or tees used in
the terminations must be included when determining the num-
ber of elbows in the piping systems.
If the combustion air intake pipe is to be installed above a
finished ceiling or other area where dripping of condensate
will be objectionable, insulation of the combustion air pipe
may be required. Use 1/2” thick closed cell foam insulation
such as Armaflex or Insultube where required.
Vent/Flue Pipe Terminations
The vent/flue pipe may terminate vertically, as through a roof,
or horizontally, as through an outside wall.
Vertical vent/flue pipe termination should be as shown in the
following figures. Refer to
Vent/Flue Pipe and Combustion
Air Pipe - Termination Locations
section in this manual or
the installation instructions for details concerning location
restrictions. The penetration of the vent through the roof must
be sealed tight with proper flashing such as is used with a
plastic plumbing vent.
NOTE: Terminate both pipes in the same pressure zone
(same side of roof, no major obstacles between pipes,
etc.).
RO
OF
LIN
E
COMBUSTION AIR INTAKE
(OPTIONAL)
*Not required for
single pipe installation
TEE (OPTIONAL)
96
” M
AX
. -
3”
M
IN
.
12” MIN
HEIGHT DIFFERENCE
BETWEEN
INTAKE AND VENT
12” MIN TO ROOF OR HIGHEST
ANTICIPATED SNOW LEVEL
STRAIGHT
ELBOWS
Horizontal vent/flue pipe terminations should be as shown in
the following figure. Refer to
Vent/Flue Pipe and Combus-
tion Air Pipe - Termination Locations
section in this manual
or the installation instructions for details concerning loca-
tion restrictions. A 2 3/8" diameter wall penetration is re-
quired for 2" diameter pipe while a 3 1/2" diameter hole is
required for 3" diameter pipe. To secure the pipe passing
through the wall and prohibit damage to piping connections,
a coupling should be installed on either side of the wall and
