Lennox Hearth Merit Series RDI-36-H - Manual (Page 16)

NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE. 16
Figure 47
Glass Doors
If glass doors are to be installed on these
fireplaces, refer to specific installation instruc-
tions packed with the glass doors. Use only the
doors that are listed for use with these fire-
places. Use of other non-listed glass door on
these fireplaces may constitute a potential fire
hazard and is not recommended.
CAUTION: CERTAIN GLASS DOORS OVERLAP
THE BLACK METAL FACING OF THE FIRE-
PLACE. IF THE FIREPLACE HAS BEEN FACED
WITH NONCOMBUSTIBLE MATERIALS, THERE
MIGHT NOT BE SUFFICIENT CLEARANCE TO
INSTALL THE GLASS DOORS OF YOUR
CHOICE. ENSURE ADEQUATE CLEARANCE IS
MAINTAINED AT ALL TIMES SO AS NOT TO
INTERFERE WITH THE INSTALLATION AND
OPERATION OF GLASS DOORS.
COLD CLIMATE INSULATION
If you live in a cold climate, it is especially
important to seal all cracks around the fire-
place opening with noncombustible material
and wherever cold air could enter the room.
Surrounding materials must be caulked where
it meets the black metal facing of the fireplace
to avoid cold air intrusion. Use noncombus-
tible caulking material only on fireplace facing
to seal. Also, the outside air inlet duct should
be wrapped with noncombustible insulation to
minimize the formation of condensation. Do
not place insulation materials on top of fire-
place or against chimney sections.
Note: A 2" air space must be preserved for all
combustible materials extending for any con-
tinuous length adjacent to the chimney.
It is especially important to insulate between
the studs of an outside chase cavity and under
the floor if the floor is above ground level. Do
not place insulation directly against the fire-
place or chimney system.
FIREPLACE FINISHES
Mantels and Trim
It is sometimes best to frame your fireplace
after it is positioned and the chimney is in-
stalled. Frame enclosure for chimney and fire-
place with 2 x 4’s (or heavier) lumber.
Note: The header may rest on the two (2) metal
top spacers on top of the unit but the header
must not be notched to fit around the spacers.
Figure 46
These fireplaces may sit directly on a combus-
tible surface. A 2" air space is required be-
tween combustible framing and the chimney.
A 1" air space is required between combustible
framing and fireplace outer wrapper. In Canada,
the minimum height for a combustible mantel
is 18" (457 mm) above the fireplace opening.
Figure 46 shows typical Canadian installa-
tions. For installations other than Canada,
combustible mantels and trim may be in-
stalled 12" above the fireplace opening as per
NFPA 211, Section 7-2.3.3. and
Figure 47. If
a mantel is of a noncombustible material, it is
exempt from these requirements as long as it
does not interfere with the installation or op-
eration of glass doors.
Hearth Extensions and Wall Shields
A hearth extension must be installed with
all fireplaces. It is to protect the combustible
floor in front of the fireplace from both radiant
heat and sparks. The hearth extension must
extend 8" beyond both sides of the fireplace
opening and 16" beyond the front (
see Figure
48 ). Use a hearth extension constructed of a
durable noncombustible material having an
equal or better (lower k value) insulating value
of k = 1.28 BTU IN/FT
2 HR
°
F or a thermal
resistance that equals or exceeds r = 0.78 HR
° F FT 2 /BTU IN. With these values, determine
the minimum thickness/material required us-
ing the formula and
Page 17.
Note: Any noncombustible material whose k
value is less than 1.28 or whose r value is more
than 0.78 is acceptable.
If the fireplace is installed on a combustible
floor, use the metal safety strips (provided)
on the floor extending half under the fire-
place and half under the hearth extension
(refer to
Figures 6 & 7).
A wall shield is required where a continuous
perpendicular side wall is within 12" of the
fireplace opening (
Figure 49 ). Use a 24" W x
30" H wall shield constructed of a durable,
noncombustible material having an equal or
better (lower k value) insulating value than k =
.54 BTU IN/FT
2 HR
°
F. At no time may a
perpendicular side wall be located closer
than 8" from the fireplace opening.
If fireplace is installed diagonally across a 90 °
corner; no wall shields are required.
Canadian Installation
Fireplace
Opening
Header
Spacer
8" Max.
(203mm)
18" Min.
(457mm)
Combustible
Mantel
Finished
Wall
Typical Installation
*Both Of These Dimensions Must Be At Least 18”
When An Unvented Gas Log Set Rated At 26,000
BTU Or Higher Is Used. (Maximum 40,000 BTU)
12"*
Min.
8 3/8"*
Fireplace
Opening
Combustible
Mantel
and Trim
12"
Max.
1 1/2"
Header
Spacer
Finished Wall