Lennox Hearth CR-3835R - Manual (Page 8)

NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE. 8
Step 8. Fireplace should be secured to side
framing members using the full length nailing
tabs at the top and bottom of the fireplace front
face. Use 8d nails or equivalent (
Figure 17 ).
Figure 17
Note: The nailing tabs and the area directly
behind the nailing tabs are exempt from the
clearances described on page 5. Maintain at
least 1/2" clearance from the firebox wrapper to
the framing at the closest point of contact,
directly adjacent to the flange.
Figure 18
Step 3. Position appropriate firestop spacer at
ceiling and fasten temporarily with two (2) 8d
nails or equivalent. If chimney penetrates ceil-
ing vertically, use flat firestop spacer, Model
F8FS-2 for FTF8 system and Model F10FS-2
for the FTF10 system*. If chimney penetrates
ceiling at 30
°
angle (offset chimney), use 30
°
firestop spacer, Model F8FS30-2 for FTF8 and
Model F10FS30-2 for FTF10 system*. Use one
nail on opposite sides to hold firestop spacer
in position. Fasten permanently, using at least
two (2) more 8d nails or equivalent, after
chimney sections have been assembled
through the firestop spacer and after any nec-
essary adjustments have been made. Firestop
spacer must be secured by at least four (4) 8d
nails or equivalent when completely installed.
Note: If there is a room above ceiling level,
firestop spacer must be installed on the bottom
side of the ceiling. If an attic is above ceiling
level, firestop spacer must be installed on top
side of ceiling joist (Figures 19 and 20 ).
Figure 19
Figure 20
Firestop Spacer
Room Above
Firestop Spacer
Attic Above
INSTALLING THE CHIMNEY SYSTEM
Step 1. Before continuing, check the operation
of the damper, as described on page 4, (
refer
to Figure 3 ).
Step 2. Using standard construction framing
techniques, construct opening for chimney
route up through the ceiling(s) and roof or
through an outside chase.
Framing must maintain adequate minimum air
space clearance at all times.
CAUTION: ALLOW MINIMUM 2" (51 MM)
CHIMNEY AIR SPACE TO COMBUSTIBLE
FRAMING MEMBERS THROUGHOUT VERTI-
CAL OR OFFSET CHIMNEY INSTALLATION
(
SEE **NOTE ).
A minimum 2" (51 mm) air space must be
reserved for all combustible materials ex-
tending for any continuous length surround-
ing the chimney (
See **Note).
Reference Figures 14 and 15 and charts Fram-
ing Dimensions for Ceiling and Roof, which
specify minimum ceiling and roof dimensions.
To determine chimney center line in new con-
struction, use plumb line from roof or ceiling
above fireplace to center of flue collar on
fireplace.
For remodeling, plumb to center of flue collar
from ceiling above, drive nail through ceiling
from below to mark position, then mark and
cut to passage from above ceiling (around
nail) (
Figure 18 ). Then plumb from ceiling or
roof level directly above hole which has just
been completed.
Step 6. Route the Class 0 air duct out the back
wall or side wall, up through the ceiling or floor
joists to an outside wall. The air duct should be
located above snow level.
Note: If the fireplace is installed against an
inside wall, the Class 0 air duct may be ex-
tended into a ventilated attic space at least 18"
(457 mm) above the attic floor. Secure the duct
hood to a vertical post with the inlet positioned
downward. Ensure nothing blocks the hood
opening. This air duct must never terminate
higher than the chimney.
Step 7. Cut or frame hole through the outside
wall for the installation of the duct inlet hood.
A 4
¹⁄₄" (114 mm) diameter hole is sufficient.
Feed the loose end of the flexible air duct
through the hole cut for the inlet hood and
attach to collar on inlet hood using two (2)
screws. Insert hood into opening. Secure in
place with nails driven through holes in hood
flange. Seal with noncombustible waterproof
silicon type caulking. If additional air duct is
needed, use Class 0 metallic air duct.
*Note: Use Models F10FS or F10FS30 when
installing FTF10 chimney in the U.S. only.
** Note: 1" (25 mm) when installed with FTF10
in the U.S. only.
Plumb Line
Note: If installing the optional collar duct kit, it
should be installed after the chimney has been
attached to the flue collar.
8d Nail Or
Equivalent