Majestic Appliances SC42A - Manual (Page 17)

17
SR/SC Series "A" Woodburning Fireplace
7412948
COMMON MATERIALS AND FACTORS
MATERIAL K* R
MINIMUM
THICKNESS
EH2416
Common Brick
0.458
5.0
1.09 0.50 in.**
0.10 5.46 in.**
(CFM Corporation)
R Value is for ¹⁄₂ inch.
* Units of K = BTU/SQ FT/HR/ßF/IN
** Thickness of Listed Material
FP533ADD
WARNING: HEARTH EXTENSION MUST BE
INSTALLED IN ACCORDANCE WITH FIGURE 23
AND MUST NOT COVER THE BOTTOM FRONT
OPENING OF THE CIRCULATING MODEL.
Alternate noncombustible materials may be used
providing the (total) thermal resistance (Rt value) of
the alternate material employed is greater than or
equal to R = 1.09. Thermal resistance (R) or thermal
conductivity (K), may be obtained from manufacturer
of the material. Factors are related by the formula K =
1/R.
T = given thickness
R = thermal resistance for a given thickness (T)
K = thermal conductivity
Noncombustible material with a lower R value may be
used, provided thickness of material is sufficiently
greater to maintain an equivalent (total) thermal
resistance (Rt).
Example of Determining Hearth Extension
Equivalents
To determine the thickness required for any new
material:
NEW
required
thickness K of new material (per inch)
K of listed material (per inch)
thickness
of listed
material
= x
Example for Common Brick
T (new) = 5.0/0.458 x 0/50 in. = 5.46 in. (new required
thickness).
Fig. 24 Hearth extension material factors.
FP550
Fig. 25 Sealing gaps.
Wall Covering
Noncombustible
Decorative
Facing
2 x 4 Header
(Do not notch
at standoffs)
Seal all cracks
between fireplace
surround and wall
materials with
noncombustible
material
Noncombustible
Decorative
Covering
Hearth Extension
Insulation
Safety Strips
Must be overlapped 1/2"
minimum
Seal crack between
fireplace and hearth
extension with
noncombustible
material
Side View