Side Wall Protection
Adjacent combustible side walls that are within dimen- sions shown in Figure 30 of fireplace opening must be protected with Wall Shield Model SP40 or a specifically built wall shield described in Figure 29.
The special wall shield design described in Figure 27 is an alternate method of adding protection to side walls and can be used in place of the SP40 with the same wall clearances specified for the SP40. Rt must =1.85 minimum.
Examples of wall shield insulation:
1.Manville - CERAFORM 126, K=.27, 1/2 inches thick
2.CFM Corporation - EH2416, K = .458, 1 inch thick required.
40"
Min.
SHR Series Woodburning Fireplaces
The top of insulation must be covered with a noncom- bustible decorative covering or a piece of .018” mini- mum sheet metal, to protect hearth extension material. (Fig. 32)
Secure the hearth extension to the floor to prevent shifting, using trim molding or other similar means at three (3) outer edges. Seal crack between the fireplace hearth and hearth extension with a noncombustible material. (Figs.
WARNING: HEARTH EXTENSION MUST BE IN- STALLED IN ACCORDANCE WITH FIGURE 26.
Alternate noncombustible materials may be used pro- viding the (total) thermal resistance (Rt value) of the al- ternate 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. (Fig. 31)
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 resis- tance (Rt).
Decorative Non- combustible Rigid Covering
FP838
40" Min.
Noncombustible Insula- tion
RT = 1.85 Min. (Manville Ceraform 126
-1/2" Thick or CFM Corporation EH2416 - 1" Thick)
Example of Determining
Hearth Extension Equivalents
To determine the thickness required for any new mate- rial:
NEW |
| K of new material (per inch) | thickness | |
required | = |
|
| X of listed |
|
| |||
thickness |
| K of listed material (per inch) | material | |
Example for Common Brick
T (new) = 5.0/0.458 x 0.50 in. = 5.46 in. (new required thickness).
Fig. 30 Noncombustible wall shield dimensions.
Hearth Installation
A hearth extension is required to protect a combustible floor in front of the fireplace. Refer to Figure 30 for minimum dimensions and mounting detail.
NOTE: Hearth Extension must not cover the air inlet opening of a fireplace.
The hearth extension described in Figure 32 must be a durable noncombustible material with a minimum (total) Rt value of 1.09; refer to Figure 31 for examples. The overall height (above a combustible floor), depth and width must be as indicated, with the extension centered to the fireplace opening.
Common Materials And Factors
Material | K* | R | Minimum | |
Thickness | ||||
|
|
|
EH2416 | 1.09 | 0.50 in.** |
|
����������������� 0.458 |
| ||
|
|
|
|
Common Brick 5.0 | 0.10 | 5.46 in.** |
|
R Value is for ��� inch.
*Units of K = BTU/SQ FT/HR/˚F/IN ** Thickness of Listed Material
FP533ADD
Fig. 31 Hearth extension material factors.
20001384 | 17 |