Vexar 368STM-1, Owners & Installation Manual, Page: 5 / 16

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Fireplace inSTallaTion
Continued
Figure 3 - Hearth Extension
Seal Gap
Fireplace
Front
Ember
Protector
Ember Protector
Seal Gap
Hearth
Extension
HEARTH ExTENSION
A hearth extension projecting a minimum of
16" in front of and a minimum of 8" beyond
each side of fireplace opening is required
to protect combustible floor construction in
front of fireplace. Use Style Crest, Inc. hearth
extension (see Accessories , page 14) HE-36
or an equal material which meets the follow -
ing specifications: a layer of noncombustible,
inorganic material having a thermal conductiv -
ity of K=0.84 BTU IN/FT, HR. F (or less) at 1"
thick. For example, if material selected has
a K factor of 0.25, such as glass fiber, the
following formula would apply:
0.25 x 1.0" = 0.30" thickness required
0.84
Thermal conductivity "K" of materials can be
obtained from the manufacturer or supplier of
the noncombustible material. If hearth exten -
sion is to be covered, use noncombustible
material such as tile, slate, brick, concrete,
metal, glass, marble, stone, etc. Provide
a means to prevent hearth extension from
shifting and seal gap between fireplace frame
and hearth extension with a noncombustible
material (see Figure 3).
WARNING: Hearth extension
is to be installed only as shown
in Figure 3.
Fireplace Front
Elevated
Fireplace Front
Raised Hearth
Seal
Gap
MANTELS
A mantel may be installed if desired (see
Figure 4). Woodwork such as wood trims,
mantels or any other combustible material
projecting from the front face must not be
placed within 9" of fireplace opening. Combus -
tible materials above 9" and projecting more
than 1
1
/
2
" from fireplace must not be placed
less than 12" from top opening of fireplace
(NFPA STD 211, Sec. 7-3.3.3).
Mantels or any other combustible material
also may come up to side edge of black metal
face of fireplace only if projection from front
face falls within limits shown in Figure 5.
12
1
/
4
" Ref.
6"
Ref.
12" Min.
9" Min.
1
1
/
2
" Max.
3" Nom.
33°
Combustible
Material
Safe
Zone for
Projection of
Combustible
Materials
Fireplace
Opening
Upper
Section of
Fireplace
Figure 4 - Mantel Clearances to
Combustible Material
FIREBOX
SAFE ZONE
Figure 5 - Projection Limits to Front Face
Top View of
Fireplace
Combustible
Material Must
Not Overlap
Front Face
2" Max.
3"
33°
7.75"
Minimum 12" from
Perpendicular Side
Wall