Lenoxx Electronics Optima 3 FS - Manual (Page 6)

PLANNING YOUR INSTALLATION
PAGE 6
FLOOR PROTECTION - Optima 3 FS
The floor protector must
meet or exceed the
minimum thermal re-
quirements as defined
on this page (see Floor
Protection/Hearth Ex-
tension Using Alternate
Material As Floor Pro-
tector). If the floor pro-
tection is to be stone,
tile, brick, etc., it must
be mortared or grouted
to form a continuous
noncombustible sur-
face. If a chimney con-
nector extends horizon-
tally over the floor, pro-
tection must also cover
the floor under the connector and at least 2" (51 mm) to either
side.
The floor protector must fully cover the area beneath the appli-
ance and extend 6” to the front, 6” to the sides, and 6” from the
back as shown in the illustration to the right (Note: When installed
at clearances less than 6”, the floor protection is only required to
extend to the wall).
FLOOR PROTECTION / HEARTH EXTENSION USING
ALTERNATE MATERIAL AS FLOOR PROTECTOR (also
see Floor Protection above for freestanding models and
Hearth Requirements, page 8 for the insert model)
The hearth pad or alternate material used as a floor/hearth
protector must be constructed of a durable noncombustible
material having an equal or better thermal conductivity value
(lower k value) of k = .84 BTU / IN FT
2 HR °F or a thermal
resistance that equals or exceeds r = 1.19 HR °F FT 2 IN/BTU
with a minimum thickness of 3/8”. With these values, deter-
mine the minimum thickness of the alternate material required
using the formula(s) and the table shown here (see chart -
Approved Alternate Materials for Floor/Hearth Protection).
Note: Any noncombustible material having a minimum thickness
of 3/8” (10 mm) whose k value is less than .84 or whose r value
is more than 1.19 is acceptable. If the alternate material used has
a higher k value or lower r value will require a greater thickness of
the material used. In some cases, if the k value is less or the r
value higher, a thinner material may be used.
Methods of determining floor protection 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: Durock  Cement is to be used for the floor protec-
tion. How thick must this material be? The following formulas
give the means of determining minimum thickness required.
T
M
= minimum thickness required for alternate material
k
M
= k value per inch of alternate material
T
L
= minimum thickness of listed material
r
M
= r value per inch of alternate material
Using the k formula:
Minimum k-value (per Inch) Specified min.
thickness of = of alternate material x thickness
alternate k-value (per inch) of listed
material of listed material material
T
M
(inches) = k
M
x T
L
.84
T
M
(inches) = 1.92 x .375 (3/8”)
.84
Answer using k: 2.29 x 0.375” = 0.858 = ~7/8”
7/8” thickness (minimum) Durock
 Cement will be required.
Using the r formula:
T
M
(inches) = 1.19 x T
L
r
M
T
M
(inches) = 1.19 x 375 (3/8”)
.52
Answer using r: 2.29 x 0. 375” = 0.858 = ~7/8”
7/8” thickness (minimum) Durock
 Cement will be required.
At times it is important to know what combination of materials
are acceptable for use as floor protection. The “R values” are
used to determine acceptable combinations of materials be-
cause “R values” are additive where r and k values are not.
“R value” = 1 = r x thickness of material used
k
Example: Given that the required “R value” for a suitable floor
protector used must be equal to or greater than “R” = r x T
L
=
1.19 x .375” = .45.
Approved Alternate Materials for
Floor/Hearth Protection (**)
Alternative
Materials
↓
Thermal Values * Minimum
Thickness
k (per inch) r (per inch) T
M
Kaowool M Board .47 2.13 * 3/8”
Micore 160  .35 2.86 * 3/8”
Micore 300  .46 2.18 * 3/8”
Durock  Cement 1.92 .52 7/8”
Hardibacker  1.95 .51 7/8”
Hardibacker 500  2.30 .44 1 1/8”
Cultered Stone
Hearthstone

2.82 .35 1 5/8”
Wonderboard 3.23 0.31 1 1/2”
Face brick 9.00 0.11 4 1/8”
Common brick 5.00 0.20 2 1/4”
Cement mortar 5.00 0.20 2 1/4”
Ceramic tile 12.5 .08 5 5/8”
Marble ~ 20.0 ~ .05 9”
Note: To convert inches to millimeters divide by .03937.
* After minimum thickness is calculated, the thickness can be
no less than 3/8” (.375” / 10mm).
(**) If the floor protector to be used is a noncombustible material
and is NOT listed on the chart above, the manufacturer of the ma-
terial must provide either the listed k-value per inch or r-value per
inch and the minimum acceptable thickness will need to be calcu-
lated per instructions on this page.
.
Top View
*Up to 6”
1 53 mm minimum
6”/
153mm
min.
6”/
153mm
min.
6”/153mm
minimum
Listed Material
Thermal Values Specified
Minimum
Thickness
k (per inch) r (per inch) T
L
Listed Material → .84 1.19 3/8” (.375)