Lennox MPD35ST-NM-B Installation Instructions Manual page 20

Remember to maintain " (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 Tables on Pages 34 & 35.
G. Support the vertical run sections -
See Step E on Page 14.
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 direc-
tion of the next vent run element. Twist elbow
sections in a clockwise direction only so as
to avoid the possibility of unlocking any of
the previously connected vent sections. See
Figure 20 on Page 14.
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.
20
It is very important that the horizontal /
inclined run be maintained in a straight (no
dips) and recommended to be in a slightly
elevated plane, in a direction away from the
fireplace of /4" rise per foot (20 mm per
meter) which is ideal, though 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 clear-
ances to combustibles: " (25 mm) at all sides
for all vertical runs; and 3" (76 mm) at the top,
" (25 mm) at sides, and " (25 mm) at the
bottom for all horizontal / inclined runs.
J. Assemble vent run to exterior wall - If not
previously measured, locate the center of the
vent at the exterior wall. Prepare an opening
as described in Step B. Assemble the vent
system to point where the terminus of the last
section is located relative to the exterior surface
to which the termination is to be attached as
shown in Figure 34 on Page 19 and Table 11
on Page 21.
K. Attach termination adapter - Attach the
adapter (SV4.5RCH - provided with the termi-
nation) to the vent section or telescoping vent
section), elbow or appliance collar as shown
in Figure 33 in the same manner as any SV4.5
vent component (refer to Step E ).
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
L. Install Firestop / Spacer at exterior wall
- When using the square termination, install
SV4.5HF (Secure Vent), SF4.5HF (Secure Flex)
Firestop / Spacer over the opening at the exterior
side of the framing, long side up, with the 3 inch
spacer clearance at the top as shown in Figure
33, and nail into place. The Firestop / Spacer
may also be installed over the opening at the
interior side of the framing.
M. Install the Square Termination
(SV4.5HT-2)
Install the square termination - For the last
step , from outside the exterior wall, slide the
collars of the termination onto the adapter until
the termination seats against the exterior wall
surface to which it will be attached. Orient
the housing of the termination with the arrow
pointed upwards. Secure the termination to
the exterior wall. The horizontal termination
must not be recessed into the exterior wall
or siding by more than the 1-1/4" (32 mm) as
shown in Figure 34.