Lennox Merit MLDVTCD-35NM Installation Instructions Manual page 14

LENNOX HEARTH PRODUCTS • MERIT
Vertical (Offset) Installation
Analyze the vent routing and determine the
quantities of vent sections and number of
elbows required. Refer to Table 14 to select
the type of vertical installation desired. Vent
sections are available in net lengths of
• 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).
Refer to Table 14 for an aid in selecting
length combinations. Elbows are available
in 90° and 45° configurations. Refer to
Figure 17 for the SV4.5E45 and SV4.5E90
elbow dimensional specifications.
Where required, a telescopic vent section
(SV4.5LA) may be used to provide the
installer with an option of installing in
tight and confined spaces or where the
vent run made up of fixed length pieces
develops a joint in a undesirable location,
or will not build up to the required length.
The SV4.5LA telescopic vent section
has an effective length of from 1 1/2 in.
(38 mm) to 7 1/2 in. (191 mm). The
SV4.5LA is fitted with a locking inclined
channel end (identical to a normal vent
section component) and a plain end with
3 pilot holes. Slip the plain end over the
locking channel end of a standard SV4.5
vent component the required distance and
secure with three (3) screws.
Maintain a minimum 1 in. (25 mm)
clearance to combustible materials for
all vertical elements. Clearances for all
horizontal elements are 3 in. (76 mm)
on top, 1 in. (25 mm) on sides and 1 in.
(25 mm) on the bottom.
1. Frame ceiling opening—Use a
plumb line from the ceiling above the
appliance to locate center of the vertical
run. Cut and/or frame an opening,
10 1/2 x 10 1/2 in. (267 x 267 mm)
inside dimensions, about this center
mark (Figure 14).
Figure 14: Framing Ceiling Opening
Min. 10 1/2 in.
(267 mm)
2. Attach vent components to
appliance—Secure Vent® SV4.5
direct vent system components are
unitized concentric pipe components
featuring positive twist lock connections
14
SERIES DIRECT-VENT GAS FIREPLACES • MLDVTCD-35 • INSTALLATION INSTRUCTIONS
®
(Figure 15).
All of the appliances covered in this
document are fitted with collars having
locking inclined channels.The dimpled
end of the vent components fit over the
appliance collar to create the positive
twist lock connection.
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 inlet of
the four inclined channels on the collar
(Figure 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
without the need for sealant or screws.
If desired a #6 x 1/2 in. screw may be
used at the joint, but it is not required as
the pipe will securely lock when twisted.
NOTE: An elbow may also be attached
to the appliance collar. Attach in the
same manner as a vent section.
3. Attach vent components to each
other—Other vent sections may be
added to the previously installed section
in accordance with the requirements
of the vertical vent figures and tables.
To add another vent component to a
length of vent run, align the dimpled
end 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
Min. 10 1/2 in. and dimple (Figure 15).
(267 mm)
4. Install firestop/spacer at ceiling—
When using Secure Vent, use SV4.5VF
firestop/spacer at ceiling joists; when
using Secure Flex
firestop/spacer. If there is living space
above the ceiling level, the firestop/
spacer must be installed on the bottom
side of the ceiling. If attic space is
above the ceiling, the firestop/spacer
must be installed on the top side of the
joist. Route the vent sections through
the framed opening and secure the
firestop/spacer with 8d nails or other
appropriate fasteners at each corner.
Maintain 1 in. (25 mm) clearance to
combustibles, framing members,
DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
5. Support the vertical vent run
Figure 15: Twist Lock Vent Pipes
Figure 16: Supporting the Vertical
, use SF4.5VF
®
and attic or ceiling insulation when
running vertical chimney sections.
Attic insulation shield (H3907) may be
used to obtain the required clearances
indicated here (Installation Accessories
on Page 32). The gap between the
vent pipe and a vertical firestop can be
sealed with non-combustible caulking.
sections—Support the vertical portion of
the venting system every 8 ft (2.4 m) above
the fireplace vent outlet. One method of
support is by utilizing field provided support
straps (conventional plumber's tape).
Secure the plumber's tape to the framing
members with nails or screws. Loop the
tape around the vent, securing the ends of
the tape to the framing. If desired, sheet
metal screws #6 x 1/2 in. length may be
used to secure the support straps to the
vent pipe(Figure 16).
NOTE: Proper venting support is
very important. The weight of the vent
must not be supported by the fireplace.
Align the dimple (four places)
of the upper vent section with
the opening of the locking
incline channel on the lower vent
section or appliance collar. Twist
vent component clockwise to
engage and seal until arrow and
dimple align.
Arrow
Dimple
Locking
Incline
Channel
Connected Vent
Sections
Appliance Collar or
Vent Section
Vent Run
Blocking
Support Straps
(Plumber's tape)
8 feet (2.4 m)
Maximum
1/2 inch (12.7
mm) minimum
clearance to
combustibles
Arrow