United States Stove Company EC95 - Manual (Page 19)

EC95 19
INSTRUCTION MANUAL ADDENDUM
This addendum is a supplement to the Installation, Operation, and Maintenance Instruction Manual for this appliance.
Do not neglect to read all instructions thoroughly.
ATTENTION: Installers of Fireplaces, Fireplace Stoves, Room Heaters, and Fireplace Inserts.
SUBJECT: Determining Equivalent Materials for Use as Hearth Extensions and Floor Protectors Over Combustible
Floors.
1. If you are not a qualified installer of the product, we suggest that you consult with a qualified installer or other
knowledgeable person for proper installation of the product. Your local building code official should also be consulted.
2. Refer to the section in the installation instructions on hearth extensions or floor protectors. Use the material speci
fied in the instructions.
3. If a listed floor protector is specified as an alternate material, consult a local dealer that sells floor protectors which
are listed by a recognized listing agency. If the solid fuel burning appliance requires one or two layers of 3/8 inch
thick millboard, a Listed floor protector may be purchased that is intended for use in place of the required number of
layers of millboard as specified in the instructions.
4. If an equivalent material for use as a hearth extension or floor protector is permitted in the installation instructions
and
a K, C, or R factor is specified, be sure (a) that the equivalent material is Listed by a recognized listing
agency, (b) that the K or C factor is equal to or less than the number specified and (c) the thickness of the
material is at least equal to the specified thickness in the installation instructions. The K factor for millboard is
equal to 0.84 BTU-inch/ (hr.) (°F) (ft 2 ), which can be used to determine equivalency under Item 3 if necessary.
5. For reference, K, C, and R factors are given for building and insulating materials in engineering handbooks such as
the ASHRAE Handbook of Fundamentals and the Standard Handbook for Mechanical Engineers by Baumeister and
Marks.
6. K, C, and R factors are explained as follows:
A. The “K” factor represents the thermal conductivity of a material and is the time rate of heat flow through a
homogeneous material under steady-state conditions, through unit area, per unit temperature gradient in the
direction perpendicular to a surface. BTU
or (Btu)(in.)
_______________ ________________________
(hr)(ft 2 )(°F/in.) (hr)(ft 2 )(°F)
B. The “C” factor represents the thermal conductance of a material at a specific thickness and is applied to a
specific homogenous material used at the stated thicknesses. (Note: The “C” factor is equal to the “K” factor
divided by the thickness of material.)
C. The “R” factor represents the thermal resistance of a material and is defined as the reciprocal of either the
“K” or “C” factor, expressed as “R per inch” (K factor reciprocal) or “R” with reference to a specific material
thickness related to a specific application (C factor reciprocal).
REFERENCES:
1. ASHRAE Handbook, 1981 Fundamentals, published by American Society of Heating, Refrigerating and Air-Condition-
ing Engineers, 1981; Chapter 23.
2. Eshbach, O. W., Handbook of Engineering Fundamentals, published by Wiley & Sons, 1936, 1952; Table 2, pp. 13-
39 to 13-43.
Note: Use of the K and C constants needs to be carefully considered since the exact number depends on the system
of units involved. The value of the constant is different under different systems of units. K is identified in some tables
as “per inch”; however, from a unit consideration, the “inch” (i.e. thickness) is actually in the numerator, not the denomi-
nator, and to determine the K factor for a specific thickness (i.e., the C factor), it is necessary to divide by the thick-
ness of the material. Other handbooks or manufacturers’ data cancel the inch of thickness in the numerator with the
square feet of area in the denominator of the K factor, resulting in a variance of 12 in the table of values or in the
manufactors’ data. An example calculation is as follows:
If the floor protector or hearth extension material is specified as one layer of 3/8 inch (0.375 inch) thick millboard with a
K factor of 0.84, the following calculations apply: