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NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT
®
PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
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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5.523 521.72 0 0 0 0 7 7
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SV4.5FA or
SV4.5FB Flashing
AND SV4.5SC
Storm Collar
SV4.5VF
Firestop/Spacer*
1 in (25.4 mm)
Minimum
Clearance to
Combustibles
SV4.5CGV-1
Termination
SV4.5L6/12/24/36/48
Vent Sections
*When using Secure Flex,
use Firestop/Spacer
SF4.5VF.
Max. 40 ft
(12.2 m)
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 20
VERTICAL TERMINATION SYSTEMS (ROOF)
See Figure 20 and Figures 30 through 32
on Page 17 and their associated Vertical
Vent Tables, which illustrate the various verti-
cal 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 5 on Page 6).
Vertical (Straight) Installation
(Figure 20)
Determine the number of straight vent sec-
tions 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
Pages 35 and 36 - Vent Sections). 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.