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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
5" (127 mm)
Radius Minimum
Flexible Vent Section
E. Attach Flex Vent to Termination -
Secure Flex components can be purchased
separately and attached to bulk lengths of
Secure Flex flexible tubing cut to size at the
job site. Secure the flexible vent to the Secure
Flex terminations in the same manner (see
Figure 45 ) as it was attached to the adapter.
See the appropriate sections and figures shown
throughout the venting section for their instal-
lation requirments.
Note: Secure Flex vent must be attached
to Secure Flex terminations only. DO NOT
substitute Secure Vent terminations or the
Secure Vent adapter for Secure Flex compo-
nents. The collars of Secure Flex terminations
and adapters have a different circumference
than that used with the Secure Vent pipe.
Additionally, Secure Flex components have
an extended length center tube for use in
attaching the flexible vent.
Figure 46
VERTICAL OR HORIZONTAL VENTING USING
SECURE FLEX KITS AND COMPONENTS
Secure Flex venting kits and components may
be used in any venting application where rigid
Secure Vent (SV4.5) direct vent components
can be used. All restrictions, clearances and
allowances that pertain to the rigid piping apply
to the flexible venting. Secure Flex kits may
not be modified; also, under no circumstances
may separate sections of flex pipe be joined
together. Secure Flex kits may be added to
the end of a vent run made up of rigid Secure
Vent (SV4.5) vent sections provided that doing
so does not violate any of the venting length,
height, routing, horizontal to vertical ratio re-
quirements or clearance considerations detailed
in this manual.
Secure Flex kits come with an included adapter
that can be fitted to the appliance collar or the
inclined channel end of the last Secure Vent
(SV4.5) vent section in a rigid system in the
exact same fashion as any other Secure Vent
section. Align the dimpled end of the adapter
over the previously installed section or appliance
collar, adjusting the radial alignment until the
four locking dimples of the adapter are aligned
with the inlets of the four incline channels of
the last vent section or collar. Push on the
adapter until it fully engages, then twist the
adapter clockwise running the dimples down
and along the incline channels until they seat
at the end of the channels.
Attach the flexible vent to the adapter as fol-
lows (see Figure 45):
A. Install the Inner Flex Pipe -
1. Install the small gear clamp loosely around
the inner flexible vent pipe, push it back out
of the way.
2. Apply a bead of Mill-Pac Black (700°F) high
temperature sealant - Catalog No. 10K81) to
the inner adapter collar, approximately 1/2 inch
from the end.
3. Pull and extend the inner flexible vent pipe.
4. Slide the inner flex pipe over the adapter
collar. Ensure the flexible vent pipe completely
engages the adapter collar to a distance of
1-3/4 inches from the end, and that it is free
from damage or tears.
5. Slide the gear clamp down and tighten it
fully to secure the flexible vent to the adapter
inner collar approximately 3/4 inch from the
end of the flex.
6. Install three screws 120 degrees apart
through the flexible vent pipe and into the
adapter collar just below the gear clamp to
provide additional security to the connection.
B. Install the Outer Flex Pipe -
1. Install the large gear clamp loosely around
the outer flexible vent pipe, push it back out
of the way.
2. Apply a bead of Mill-Pac Black (700°F) high
temperature sealant - Catalog No. 10K81) to
the outer adapter collar; to the grooves of the
collar which extend approximately 1 inch from
the end and to the flat surface, approximately
1-3/8 inches from the end.
3. Pull and extend the outer flexible vent pipe.
4. Slide the outer flex pipe over the adapter
collar. Ensure the flexible vent pipe completely
engages the adapter collar to a distance of 1³⁄₄
inches from the end, and that it is free from
damage or tears.
5. Slide the gear clamp down and tighten it
fully to secure the flexible vent to the adapter
outer collar approximately 3/4 inch from the
end of the flex.
6. Install three screws 120 degrees apart
through the flexible vent pipe and into the
adapter collar just below the gear clamp to
provide additional security to the connection.
C. Route Flex Vent -
Ensure that the flex vent is properly routed to
provide the required clearance. Do Not allow
the flexible vent to bend in a radius tighter than
5" (127 mm). Refer to Figure 46. Support
horizontal sections of flex with metal straps at
2 foot (0.61 m) intervals.
D. Install Firestop/Spacers at ceilings and walls -
When Secure Flex penetrates a wall or ceiling,
a firestop/spacer is required: use the SF4.5 VF
firestop/spacer for ceilings and the SF4.5 HF
firestop/spacer for walls.
GEAR
CLAMPS
Adapter
(SV4.5RF)
Apply ONLY MIL-PAC BLACK HIGH
TEMPERATURE SEALANT (Catalog No.
10K81) to the outside surface of both
collars of the adapter (be especially
careful to fill the grooves of the outer
collar to be covered by the flexible
pipe) and slide flexible pipe over
inner and outer adapter collars.
NOTE: OUTER PIPE IS PULLED AWAY TO
SHOW THE DETAIL OF THE INNER PIPE
FLEX VENT
1-3/4 in. (44 mm)
Flexible Pipe and
Adapter Outer
Collar Overlap
1-3/4 in. (44 mm)
Flexible Pipe and
Adapter Inner
Collar Overlap
SECURING SCREW
(3 PLACES EQUALLY SPACED
JUST BELOW GEAR CLAMP)
Attach Adapter to Appliance
Collar, or Secure Vent Sections
SECURING SCREW
(3 PLACES EQUALLY SPACED
JUST BELOW GEAR CLAMP)
Figure 45