Jøtul C 450 - Appendix A; Alternate Floor Protection

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138344_Rev_D - C450 Kennebec 8.2.10
Appendix A:
Alternate Floor Protection
All floor protection materials must be non-combus-
tible i.e.. metal, brick, stone, or mineral fiberboards. No
combustible material may be used to protect the floor in
front of the fireplace insert.
Follow this procedure to determine if a proposed
alternate floor material meets the requirements listed in
this manual.
R-value = Thermal Resistance
K-value = Thermal Conductivity
C-value = Thermal Conductance
1. Convert the specification to R-value;
a. If R-value is given, no conversion is needed.
b. If K-value is given with a required thickness
(t) in inches: R = 1/K X T.
c. If C-value is given: R = 1/C.
2. Determine the R-value of the proposed alternate floor
protector.
a. Use the formula in Step 1 to convert values not
expressed as “R ”.
b. For multiple layers, add R-values of each layer to
determine overall R-value.
3. If the overall R-value of the system is greater than the
R-value of the specified floor protector, the alternate is
acceptable.
Example:
The specified floor protector should be 3/4” thick material
with a K-factor of 0.84. The proposed alternate is 4” brick
with a C-factor of 1.25 over 1/8 inch mineral board with a
K-factor of 0.29.
Step A. Use formula above to convert specifications
to R-value. R = 1/K x T = 1/.84 x .75 = .893
Step B. Calculate r of proposed system.
4 ” brick of C - 1.25, therefore
R brick = 1/C = 1/1.25 = 0.80
1/8 ” mineral board of K = 0.29, therefore
R mineral board = 1/.29 x 0.125 = 0.431
Total R = R brick + R mineral board =
0.8 + 0.431 = 1.231
Step C. Compare proposed system R = 1.231 to
specified R of 0.893. Since R is greater than
required, the system is acceptable.
Definitions:
Thermal Conductance =
C = Btu = W
(Hr)(ft2)(f) (m2)(k)
Thermal Conductivity =
K = Btu = W = (Btu)
(Hr)(ft2)(f) (m2)(k) (hr)(ft)(f)
Thermal Resistance =
R = Btu = (m2)(k) = (Btu)(inch)
(Hr)(ft2)(f) W (hr)(ft2)(f)
The Jøtul C450 Fireplace Insert requires floor protection
having a minimum insulating R-value of 2.92.