5700 act wood stove, Floor protection (cont’d), Alternate materials worksheet – Hearth and Home Technologies 820-0721 User Manual
Page 8
5700 ACT Wood Stove
Page 8
September 1, 2008
R
250-7090e
r =
x T
1
k
r =
x T
1
K x 12
k-factor is given with a required thickness (T) in inches:
K-factor is given with a required thickness (T) in inches:
r-factor is given with a required thickness (T) in inches: r = r x T
r-value given - no conversion needed.
FLOOR PROTECTION (Cont’d)
How to determine if alternate floor protection materials are acceptable:
All floor protection must be non-combustible (i.e., metals, brick, stone, mineral fiber boards, etc.). Any organic materials
(i.e., plastics, wood paper products, etc.) are combustible and must not be used. The floor protection specified includes
some form of thermal designation such as r-value (thermal resistance) or k-factor (thermal conductivity).
PROCEDURE:
1. Convert specification to r-value:
2. Determine the r-value of the proposed alternate floor protector.
i. Use the formula in step (1) to convert values not expressed as “r”.
ii. 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 inch thick material with a k-factor of 0.84. The proposed alternate is
4” brick with an r-factor of 0.2 over 1/8” mineral board with a k-factor of 0.29.
Step (b): Calculate r of proposed system.
=
1
r =
x T
1
x 0.75 = 0.893
k
.84
rbrick = 0.2 x 4 = 0.8
4" brick of r = 0.2, therefore:
1/8" mineral board of k = 0.29, therefore:
rmineral board = 1
0.29
x 0.125 = 0.431
rtotal = rbrick + rmineral board = 0.8 + 0.431 = 1.231
Step (c): Compare proposed system rtotal of 1.231 to specified r of 0.893. Since proposed system rtotal is greater than
required, the system is acceptable.
DEFINITIONS
(ft
2
)(hr)(
o
F)
btu
r =
btu(in)
ft
2
(hr)(
o
F)
= K x 12
k =
1
k
r = (ft
2
)(hr)(
o
F)
(btu)(in)
=
K =
btu(ft)
ft
2
(hr)(
o
F)
ALTERNATE MATERIALS WORkSHEET
Step (a): Use formula above to convert specification to r-value.