19
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT PLUS
®
DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
Figure 32: Typical Horizontal Vent Installation
V
ertical
Rise
SV4.5E90
Elbow
Horizontal / Inclined Run
SV4.5HT-2
Termination
Firestop/Spacer
SV4.5L6/12/24/36/48
Vent Sections
Support bracket spacing
every 5 ft (1.52 m)
See Figure 24 on Page 15 for
vertical vent section support.
SV4.5HT-2
Termination
Support
Brackets
Building
Support
Framing
Ceiling
Fireplace
Exterior
Wall
Exterior
Wall
HORIZONTAL (OUTSIDE WALL)
TERMINATION SYSTEM
Figure 32, and Figures 35 to 41 on
Pages 21 to 23 and their associated
Horizontal Vent Table illustrate the various
horizontal venting confi gurations that are
possible for use with these appliances.
Secure Vent
®
pipe applications are shown in
these fi gures; Secure Flex
®
pipe may also be
used. A Horizontal 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
of these horizontal vent systems terminate
through an outside wall. Building Codes limit
or prohibit terminating in specifi c areas.
Refer to Figure 7 on Page 7 for location
guidelines.
Secure Vent SV4.5 direct vent system
components are unitized concentric pipe
components featuring positive twist lock
connection, (refer to Figure 21 on Page 15).
All of the appliances covered in this document
are fi tted with collars having locking inclined
channels. The dimpled end of the vent
components fi t over the appliance collar to
create the positive twist lock connection.
A. Plan the vent run—Analyze the vent
routing and determine the types and quantities
of sections required 4 1/2 in. (114 mm),
10 1/2 in. (267 mm), 22 1/2 in. (572 mm),
34 1/2 in. (876 mm) and 46 1/2 in. (1181 mm)
net section lengths are available. It is
recommended that you plan the venting so
that a joint does not occur in the ceiling or roof
joists. Allow for elbows as indicated in Figure 23
on Page 16.
Maintain a minimum 1 in. (25 mm) clearance
to combustibles on the vertical sections.
Clearances for the horizontal runs are; 3 in.
(76 mm) on top, 1 in. (25 mm) on sides, and
1 in. (25 mm) at the bottom.
B. Frame exterior wall opening—Locate
the center of the vent outlet on the exterior
wall according to the dimensions shown in
Figure 12 on Page 11. Cut and/or frame an
opening, 10 1/2 in. x 12 1/8 in. (267 mm
x 308 mm) inside dimensions, about this
center.
C. Frame ceiling opening—If the
vertical route is to penetrate a ceiling, use
plumb line to locate the center above the
appliance. Cut and/or frame an opening,
10 1/2 in. x 10 1/2 in. (267 mm x 267 mm)
inside dimensions, about this center (refer to
Figure 20 on Page 15).
D. Attach vent components to appliance—To
attach a vent component to the appliance
collar, align the dimpled end over the collar,
adjusting the radial alignment until the four
locking dimples are aligned with the inlets of
the four incline channels on the collar (refer to
Figure 21 on Page 15).
Push the vent component against the
collar until it fully engages, then twist the
component clockwise, running the dimples
down and along the incline channels until they
seat at the end of the channels. The unitized
design of the Secure Vent components will
engage and seal both the inner and outer pipe
elements with the same procedure. Sealant
and securing screws are not required.
Note: An elbow may also be attached to the
appliance collar. Attach in the same manner
as you would a vent section.
E. Attach vent components to each other—
Other vent sections may be added to the
previously installed section in accordance
with the requirements of the vent tables.
To add another vent component to a length
of vent run, align the dimpled end of the
component over the inclined channel end of
the previously installed section, adjusting
the radial alignment until the four locking
dimples are aligned with the inlets of the four
incline channels of the previous section. Push
the vent component against the previous
section until it fully engages, then twist the
component clockwise running the dimples
down and along the incline channels until they
seat at the end of the channels.This seating
position is indicated by the alignment of the
arrow and dimple as shown in Figure 21 on
Page 15.
F. Install fi restop/spacer at ceiling—
When using Secure Vent, use SV4.5VF
fi restop/spacer at ceiling joists; when using
Secure Flex
®
, use SF4.5VF fi restop/spacer. If
there is living space above the ceiling level,
the fi restop/ spacer must be installed on the
bottom side of the ceiling. If attic space is
above the ceiling, the fi restop/ spacer must
be installed on the top side of the joist. Route
the vent sections through the framed opening
and secure the fi restop/spacer with 8d nails
or other appropriate fasteners at each corner.
Remember to maintain 1 in. (25 mm)
clearance to combustibles, framing
members, and attic or ceiling insulation
when running vertical chimney sections.
G. Support the vertical run sections—
On the vertical run, support the venting
system every 8 feet (2.4m) above the
fi replace vent outlet with fi eld provided
support straps (Plumber's tape). Attach the
straps to the vent pipe and secure to the
framing members with nails or screws. See
Figure 22 on Page 15.
H. Change vent direction—At transition
from or to a horizontal/inclined run, install
the SV4.5E45 and SV4.5E90 elbows in the
same manner as the straight vent sections.
The elbows feature a twist section to allow
them to be routed about the center axis
of their initial collar section to align with
the required direction of the next vent
run element. Twist elbow sections in a
clockwise direction only so as to avoid
the possiblity of unlocking any of the
previously connected vent sections. See
Figure 23 on Page 16.
I. Continue installation of horizontal/
inclined sections—Continue with the
installation of the straight vent sections in
horizontal/inclined run as described in Step
E. Install support straps every 5 ft. (1.52 m)
along horizontal/inclined vent runs using
conventional plumber’s tape. See Figure 32,
It is very important that the horizontal/
inclined run be maintained in a straight
(no dips), slightly elevated plane. The
recommended incline is approximately
1/4 in. per foot (20 mm per meter)
horizontal, in a direction away from the
fi replace. The rise per foot run ratios that
are smaller are acceptable all the way down
to at or near level. Use a carpenter’s level to
measure from a constant surface and adjust
the support straps as necessary.
It is important to maintain the required
clearances to combustibles: 1 in. (25 mm)
at all sides for all vertical runs; and 3 in.
(76 mm) at the top, 1 in. (25 mm) at sides,
and 1 in. (25 mm) at the bottom for all
horizontal/inclined runs.
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