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Example: Given that the required "R value" for
a suitable hearth extension used must be equal
to or greater than:
"R" = r x T
= 3.70 x " = 3.70.
L
If it is desired to elevate a marble hearth exten-
sion to a level of 5" or more above the floor
surface. What combination of noncombustible
materials can be used to accomplish this?
If common brick is used so that the 3
dimension is the height, "R" for the common
brick becomes:
"R"
= r x T
= 0.20 x 3
" = .70
M
M
Using " of mortar to set the brick, "R" for the
mortar is calculated as follows:
"R"
= r x T
= 0.20 x
" = .10
M
M
A
" marble slab set in
" mortar covers the
brick, "R" for the marble and mortar becomes:
"R"
= r x T
= 0.09 x
" = .068
M
M
"R"
= r x T
= 0.20 x
" = .10
M
M
The sum of all "R values" is:
.70 + .10 +. 068 + .10 = .968
This would not be an acceptable combination
of material for the hearth extension since the
total calculated "R value" of the materials used
is under the required "R value" of 3.70. An
additional layer of insulating materials must
be used.
WARNING: THE CRACK BETWEEN THE
FIREPLACE AND THE HEARTH EXTEN-
SION MUST BE SEALED WITH A NON-
COMBUSTIBLE MATERIAL.
WARNING: WHEN INSTALLING HEARTH
EXTENSION IN FRONT, THE FIREPLACE
MUST BE RAISED IF HEIGHT OF HEARTH
EXTENSION EXCEEDS 7
BOTTOM OF FIREPLACE ( FIGURE 45 ).
7
Max. Thickness Of Hearth Extension When
"
Non-Circulating Models Are On The Floor
Figure 45
Secure the hearth extension to the floor to
prevent possible shifting.
FINISH TO YOUR TASTE
There are a wide variety of "finished looks" for
these fireplaces, from formal wall decor with
elaborate mantels to rustic wood paneling or
warm brick facings.
Only noncombustible materials like stone, tile,
brick, etc., may overlap the black front facing.
Do not extend these materials beyond the black
facing and into the firebox area. Be sure not to
interfere with the installation and operation of
glass doors or block the upper or lower grilles.
Seal all joints between the black facing and wall
surrounds to prevent air intrusion. Use non-
combustible caulking material only to seal the
black metal facing to the surround material on
the finished wall.
Combustible materials may project beyond the
sides of the fireplace opening as long as they
are kept within the shaded areas illustrated in
Figure 46 .
Combustible
Materials
Allowed In
Shaded Area
"Safe Zone"
" ABOVE THE
20"
Figure 46
NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.
"
Fireplace
14"
1"
45
Min. Distance To
Protected Side Wall
14"
Min. Distance To
20"
Unprotected Side Wall
INSTALLATION COMPONENTS
The following items are available for use in the
installation of this appliance.
Outside Combustion Air Kits
(with duct)
81L87
(without duct)
81L88
Firestop Spacer (30 )
63L37
Offset/ Return
Package (30 )
63L23
Combination
Offset/Return Elbow
63L34
FOAK
FOAK-LD
F10FS30-2
FTF10-ES30
FTF10-OR15
17
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