14
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT PLUS
®
DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
Figure 20
Figure 22
Figure 21
Support the vertical portion of the venting
system every 8 feet (2.4m) 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" length may be
used to secure the support straps to the vent
pipe. See
Figure 22
.
Vertical (Offset) Installation
Analyze the vent routing and determine the
quantities of vent sections and number of
elbows required. Refer to
Vertical Vent Figures
and Tables on
Page 17
to select the type of
vertical installation desired. Vent sections are
available in net lengths of 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). Refer to the
Vent Section Length Chart on
Page 14
for an
aid in selecting length combinations. Elbows are
available in 90° and 45° configurations. Refer
to
Figure 23
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 in 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" (38 mm)
to 7 1/2" (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 screws.
Maintain a minimum 1" (25 mm) clearance to
combustible materials for all vertical elements.
Clearances for all horizontal elements are 3"
(76 mm) on top, 1" (25 mm) on sides and 1"
(25 mm) on the bottom.
A.
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" (267 mm x 267
mm) inside dimensions, about this center mark
(
Figure 20
).
B.
Attach vent components to appliance
- Secure Vent
®
SV4.5 direct vent system
components are unitized concentric pipe
components featuring positive twist lock
connections (
see
Figure 19
)
. 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
(
refer to
Figure 21
). 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" 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
you would a vent section.
C. 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 and
dimple as shown in
Figure 21.
d.
Install firestop/spacer at ceiling -
When
using Secure Vent, use SV4.5VF firestop/spacer
at ceiling joists; when using Secure Flex
®
, use
SF4.5VF 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.
Remember to maintain 1" (25 mm) clearance
to combustibles, framing members, and attic
or ceiling insulation when running vertical
chimney sections. Attic insulation shield
(96K94) may be used to obtain the required
clearances indicated here. See installation
accessories table on
Pages 36 and 37
. The gap
between the vent pipe and a vertical firestop
can be sealed with non-combustible caulking.
E.
Support the vertical vent run sections -
NOTE:
Proper venting support is very important.
Blocking
Support Straps
(Plumber's tape)
8 feet (2.4 m)
Maximum
1/2 inch (12.7
mm) minimum
clearance to
combustibles
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.
dimple
Locking Incline
Channel
Connected Vent
Sections
Arrow
Arrow
Appliance Collar or
Vent Section
Min. 10-1/2"
(267 mm)
Min. 10-1/2"
(267 mm)
Roof
Framing
Ceiling
Framing
Plumb
Bob
