TOA Electronics CST38MH - Manual (Page 19)

19
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Figure 46
hearth extension dimensions
a 16"
b 8-1/"
c 8"
d 44-1/"
methods of determining hearth extension and wall shield
equivalents - To determine the thickness required for the alternate
material when either the "k" value or "r" value is known, use either the
k formula or r formula.
example: If Micore 160 is to be used for the hearth extension fireplace,
how thick must this material be?
k
M
= k value per inch of alternate material
r
M
= r value per inch of alternate material
T
M
= minimum thickness required for alternate material
T
s
= standard thickness of the alternate material
k
L
= k value per inch of listed material
r
L
= r value per inch of listed material
T
L
= minimum thickness of listed material
Note: An asterix "*" indicates, it is a value taken from Table 5.
using the k formula:
minimum k-value (per Inch) of specified min.
thickness of = alternate material (k
M
) x thickness
alternate k-value (per inch) of listed
material (T
M
) of listed material (k
L
) material (T
L
)
T
m
(inches) = k
m
x T
l
*.84
T
m
(inches) = *.35 x 1"
*.84
.416 (inches)= .416 x 1"
Answer - The minimum required thickness of the Micore 160 is .417," there-
fore round up to nearest standard thickness available which is 1/2."
minimum r-value (per Inch) specified min.
thickness of = of listed material x thickness
alternate r-value (per inch) of listed
material of alternate material material
T
m
(inches) = r
l
x T
l
r
m
T
m
(inches) = *1.19 x 1"
* .86
.417 (inches)= .416 x 1"
Answer - The minimum required thickness of the Micore 160 is .417," there-
fore round up to nearest standard thickness available which is 1/2."
using the r formula:
note: To convert inches to millimeters divide by .03937.
listed material
k (per inch) r (per inch) listed min.Thickness
listed material .84
K
L
1.19
r
L
1 "
T
L
** approved alternate materials for floor/hearth Protection
alternativematerials Thermal Values minimumThickness
(rounded to nearest 1/8 inch)
k (per inch)
K
M
r (per inch)
r
M
min. Thickness
T
M
Kaowool m board .47 .13 .56" (1/")
micore 160™
U.S. Gypsum
.35 .86 .4" (3/8")
micore 300™
U.S. Gypsum
.46 .17 .55" (1/")
durock™ cement board
U.S. Gypsum
1.9 .5 .9" (-1/4")
hardibacker™ 1.95 .513 .3" (-3/8")
hardibacker 500™ .30 .435 .74" (-3/4")
cultered stone hearth-
stone™
.8 .355 3.36" (3-3/8")
wonderboard 3.3 .31 3.85" (3-7/8")
super firetemp m
Johns-Manville
.61 1.64 .73" (3/4")
super firetemp l
Johns-Manville
.54 1.85 .64" (5/8")
face brick 9.00 .111 10.71" (10-3/4")
common brick 5.00 .0 5.95" (6")
cement mortar 5.00 .0 5.95" (6")
ceramic tile 1.5 .08 14.88" (14-7/8")
marble ~11 ~.09 13.10" (13-1/8")
Table 5
** If the hearth extension material(s) that is intended to be used is NOT listed
on Table 5, the material can still be used if the material(s) is noncombustible.
However, the manufacturer of the material must provide either the listed k-value
per inch or r-value per inch with listed thickness so that the minimum thickness
required for the hearth can be calculated (per instructions on this Page and/or
as specified in the NFI Certification manuals).
Note: Also see NFI (National Fireplace Institute) Certification Manuals showing
other exceptable caluculation methods and acceptable alternate materials
which can be used.
B
A C
C
Protected
Side Wall
Model CST-38
D
40"
40"
a
b
d
c c
wall shield required
where less Than 18".
adjacent wall is never
allowed closer
Than 8".