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13
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
VERTICAL TERMINATION SYSTEMS (ROOF)
See Figure 15 on Page 13 and Figures 23-
25 on Pages 16 and 17 and their associated
Vertical Vent Tables which illustrate the various
vertical venting configurations that are possible
for use with these appliances. Secure Vent™
pipe applications are shown in these Figures;
Secure Flex™ pipe may also be used. A Vertical
Vent Table summarizes each system’s minimum
and maximum vertical and horizontal length
values that can be used to design and install the
vent components in a variety of applications.
Both these vertical vent systems terminate
through the roof. The minimum vent height
above the roof and/or adjacent walls is speci-
fied in ANSI Z223.1-(latest edition) (In Canada,
the current CAN/CSA-B149.1 installation code)
by major building codes. Always consult your
local codes for specific requirements. A general
guide to follow is the Gas Vent Rule (refer to
Figure 4B on Page 6).
A vent restrictor may need to be installed when
vertical termination is used. See Installation of
Vent Restrictor on Page 12 for guidelines.
Vertical (Straight) Installation
Determine the number of straight vent sections
required. 4-1/2" (114 mm), 10-1/2" (267 mm),
22-1/2" (572 mm), 34-1/2" (876 mm) and 46-
1/2" (1181 mm) net section lengths are available
(see Tables on this page and Page 34 - Vent
Sections). It is recommended that you plan the
vent lengths so that a joint does not occur at
the intersection of ceiling or roof joists. Refer
to the Vent Section Length Chart.
LENNOXHEARTHPRODUCTS•MERIT
®
SERIESDIRECT-VENTCONTEMPORARYDESIGNGASFIREPLACES•MODELMLDVTCD-35•INSTALLATIONINSTRUCTIONS
Note: Convert inches into metric equivalent
measurement, as follows:
Millimeters (mm) = Inches x 25.4
Centimeters (cm) = Inches x 2.54
Meters (M) = Inches x .0254
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5.34 526.3 0 2 1 0 0 3
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15 52.4 1 0 0 0 1 2
5.55 526.4 0 1 2 0 0 3
75 57.4 0 0 1 1 0 2
66 52.5 0 2 2 0 0 4
5.76 526.5 0 0 3 0 0 3
96 57.5 0 0 0 2 0 2
27 6 1 0 3 0 0 4
5.37 521.6 1 0 0 2 0 3
5.97 526.6 0 1 0 2 0 3
18 57.6 0 0 0 1 1 2
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39 57.7 0 0 0 0 2 2
69 8 1 0 1 2 0 4
5.79 521.8 1 0 0 0 2 3
201 5.8 2 0 0 0 2 4
5.301 526.8 0 0 0 3 0 3
801 9 1 0 0 3 0 4
411 5.9 0 2 0 0 2 4
711 57.9 1 0 5 0 0 6
5.811 578.9 1 1 0 3 0 5
621 5.01 0 0 1 3 0 4
5.031 578.01 1 0 1 3 0 5
531 52.11 0 0 6 0 0 6
831 5.11 0 0 0 4 0 4
5.931 526.11 0 0 0 0 3 3
5.241 578.11 1 0 0 4 0 5
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5.061 573.31 0 2 0 0 3 5
5.271 573.41 0 0 0 5 0 5
771 57.41 1 0 0 5 0 6
381 52.51 0 1 0 5 0 6
681 5.51 0 0 0 0 4 4
5.091 578.51 1 0 0 0 4 5
5.691 573.61 0 1 0 0 4 5
5.502 521.71 0 1 1 5 0 7
702 52.71 0 0 0 6 0 6
5.112 526.71 1 0 0 6 0 7
5.712 521.81 0 1 0 6 0 7
5.922 521.91 0 0 1 6 0 7
5.232 573.91 0 0 0 0 5 5
732 57.91 1 0 0 0 5 6
5.142 521.02 0 0 0 7 0 7
642 5.02 1 0 0 7 0 8
252 12 0 1 0 7 0 8
462 22 0 0 1 7 0 8
672 32 0 0 0 8 0 8
972 52.32 0 0 0 0 6 6
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082 573.32 1 0 0 8 0 9
5.382 526.32 1 0 0 0 6 7
5.982 521.42 0 1 0 0 6 7
5.103 521.52 0 0 1 0 6 7
5.013 578.52 0 0 0 9 0 9
513 5.62 1 0 0 9 0 01
5.523 521.72 0 0 0 0 7 7
033 5.72 1 0 0 0 7 8
633 82 0 1 0 0 7 8
543 57.82 0 0 0 01 0 01
5.943 521.92 1 0 0 01 0 11
273 13 0 0 0 0 8 8
5.673 573.13 1 0 0 0 8 9
5.973 526.13 0 0 0 11 0 11
5.814 578.43 0 0 0 0 9 9
324 52.53 1 0 0 0 9 01
564 57.83 0 0 0 0 01 01
Effective Vent Length
Model Effective Length
SV4.5L6 4-1/2"
SV4.5L12 10-1/2"
SV4.5L24 22-1/2"
SV4.5L36 34-1/2"
SV4.5L48 46-1/2"
Table 7
Figure 15
SV4.5CGV-1
Termination
SV4.5FA OR
SV4.5FB Flashing
AND SV4.5SC
STORM COLLAR
SV4.5VF
Firestop/Spacer
SV4.5L6/12/24/36/48
Vent Sections
40' Max
(12.2 M)
1" (25.4 mm)
Minimum
Clearance to
Combustibles
When using Secure Flex
use Firestop/Spacer
SF4.5VF