7
Montpelier Medium Insert
30004403
How to Determine if Alternate Floor
Protection Materials are Acceptable
All floor protection must be noncombustible (i.e. met-
als, 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 (ther-
mal conductivity).
Procedure:
1. Convert specifications to R-value:
i. R-value given - no conversion needed.
ii. k-factor is given with a required thickness (T) in
inches:
iii. K-factor is given with a required thickness (T) in
inches:
iv. r-factor is given with a required thickness (T) in
inches: R = r x T
FP1095
hearth protection
2/08 djt
A
B
C
B
United States
Canada
A. 18”* (460 mm)
18” (460 mm)
B. 8”
(203 mm)
8”
(203 mm)
C. 44
³⁄₄
” (1137 mm) 44
³⁄₄
” (1137 mm)
FP1095
Fig. 5
Unless your fireplace and hearth are constructed over
a dirt floor (or unpainted concrete over dirt), you must use a
floor protector that satisfies the above requirements.
Typically, thermal protection with the above dimensions will be
required. The equivalent of 1.25” (32 mm) of a material with a k-
value 0.84 (or a total
R-value of 1.49
) is necessary.
If the insert is elevated 8
¹⁄₂
” (216 mm) or more above a combus-
tible hearth, thermal protection is not needed. However, spark and
ember protection is still necessary.
*If the insert is elevated 3” (76 mm) or more, this dimension may
be reduced to 16” (406 mm) (US only) beyond which no thermal
protection is necessary.
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 alter-
nate is acceptable.
EXAMPLE:
The specified floor protector should be 1
¹⁄₄
-
inch thick material with k-factor of 0.84. The proposed
alternate is 4” brick with an r-factor of 0.2 over 1/4”
mineral board with a k-factor of 0.29
Step a: Use formula above to convert specification to
R-value:
Step b: Calculate R of proposed system.
4” brick of r = 0.2, therefore:
R
brick
= 0.2 x 4 = 0.8
1/8” mineral board of k = 0.29, therefore
R
mineralboard
= x 0.25 = 0.431
R
total
= R
brick
+ R
mineralboard
= 0.8 + 0.431 = 1.66
Step c: Compare proposed system Rtotal of 1.66 to
specified R of 1.49. Since proposed system Rtotal is
greater than required, the system is acceptable.
Definitions
R = x T
1
K x 12
R = x T = x 1.25 = 1.49
1
k
1
0.84
1
0.29
r = =
(ft
2
)(hr)(°F)
(Btu)(in)
1
k
(Btu)(ft)
(ft
2
)(hr)(°F)
K =
k = = K x 12
(Btu)(in)
(ft
2
)(hr)(°F)
R =
(ft
2
)(hr)(°F)
Btu
R = x T
1
k
Optional Surround Packages
Custom-made surround panels may be made from any
noncombustible material.
MHSC offers both steel and cast iron Surround panel
kits, each in two sizes.
Enclosure Area
Georgian Cast Surround:
30DVSGTKCB, 30DVSGTKB
........................................ 30
¹⁄₄
x 41 (768 x 1041 mm)
Mead Cast Surround:
MEAD3CB, MEAD3EB, MEAD3BS
................................ 28
¹⁄₄
” x 41
¹¹⁄₁₆
” (718 x 1059 mm)
Caprice Cast Adjustable Profile Surround:
CAPCB, CAPEB ................25” x 35” (635 x 889 mm )
Bevel Cast Trim Surround:
LHEABSL ...................27
⁷⁄₈
” x 40
³⁄₄
” (708 x 1035 mm)
Steel Surround:
LHE30SSB .................... 27” X 38
¹⁄₄
” (686 X 972 mm)
LHE30SLB, LHE30SLGA ...........................................
......................................28
¹⁄₄
” x 41” (718 x 1041 mm)