15
WMC Series Woodburning Fireplace
20000583
1. Manville - CERAFORM 126, K=.27,
1/2 inches thick
2. CFM Corporation - EH2416, K = .458,
1 inch thick required.
Hearth Installation
A hearth extension is required to protect a combustible
floor in front of the fireplace. Refer to Figure 24 for
minimum dimensions and mounting detail.
NOTE: Hearth Extension must not cover the air
inlet/outlet opening of a fireplace.
The hearth extension described in Figure 24 must be a
durable noncombustible material with a minimum (to-
tal) Rt value of 1.09; refer to Figure 25 for examples.
The overall height (above a combustible floor), depth
and width must be as indicated, with the extension
centered to the fireplace opening.
The top of insulation must be covered with a noncom-
bustible decorative covering
or
a piece of .018” mini-
mum sheet metal, to protect hearth extension material.
(Fig. 24)
Secure the hearth extension to the floor to prevent shift-
ing, using trim molding or other similar means at three
(3) outer edges. Seal crack between the fireplace hearth
and hearth extension with a noncombustible material.
(Figs. 22 and 26)
WARNING: HEARTH EXTENSION MUST BE IN-
STALLED IN ACCORDANCE WITH FIGURE 24 AND
MUST NOT COVER THE BOTTOM FRONT OPENING
OF THE CIRCULATING MODEL.
Alternate noncombustible materials may be used provid-
ing the (total) thermal resistance (Rt value) of the alter-
nate material employed is greater than or equal to R =
1.09. Thermal resistance (R) or thermal conductivity (K),
may be obtained from manufacturer of the material. Fac-
tors are related by the formula K = 1/R.
T = given thickness
R = thermal resistance for a given thickness (T)
K = thermal conductivity
Noncombustible material with a lower R value may
be used, provided thickness of material is sufficiently
greater to maintain an equivalent (total) thermal resis-
tance (Rt).
Minimum Wall Clearances
WITH
Noncombustible
Surround Facing
WITHOUT
Noncombustible
Surround Facing
Minimum Hearth Extension Dimensions
(for On-Site Construction)
G
H
G
J
Seal cracks
between the
fireplace
and hearth
extension with
noncombustible
material
Safety strips
must overlap
���
" minimum
May install
noncombustible
decorative
covering
OR
.018" min.
sheet metal
FIREPLACE
HEARTH
COMBUSTIBLE
FLOOR
MINIMUM
INSULATION
VALUE "R"
4" MIN.
FP594A
WMC combustible min.
1/29/99 djt
FIREBOX
OPENING
A -
Min. clearance
to combustible
perpendicular wall
B -
Min. clearance
to combustible
perpendicular wall when
using noncombustible wall shield*
SIDE
WALL
SIDE
WALL
F
**
C
**
E
E
D
4" BRICK
(Example material)
Combustible material permitted within shaded area.
* Noncombustible wall shield requires 1" Majestic EH2416
insulation (minimum R Value = 1.85) between decorative
noncombustible rigid covering and combustible wall.
Minimum height and width is 40" x 40".
** Dimension/degree of angle will vary depending on thickness
of noncombustible surround facing.
4"
Shaded area starts
1/2" away from
edge of unit
FP594A
Fig. 24
Combustible side wall protection and hearth extension dimensions.
A
B
C
D
E
F
G
H
J
WMC36
16"
12"
48°
41°
18"
14"
7
³⁄₄
"
16"
48"
406 mm 305 mm
457 mm 356 mm 197 mm 406 mm 1219 mm
WMC42
20"
12"
42°
35°
18"
14"
11
¹⁄₂
"
20"
61
¹⁄₂
"
508 mm 305 mm
457 mm 356 mm 292 mm 508 mm 1562 mm