Desa (V)JM42, (V)JM50, (V)JM36 Fireplace Installation, Continued, Hearth Extension, Mantels

FIREPLACE INSTALLATION

Continued

Note: For outdoor installations, the fireplace en- closure must allow for adequate drainage and fresh air ventilation. It is recommended that a sealed, corrosion resistant catch pan with provision for drainage be installed under the fireplace within the fireplace enclosure.

HEARTH EXTENSION

A hearth extension projecting a minimum of 20" in front of and a minimum of 12" beyond each side of the fireplace opening is required to protect combustible floor construction in front of the fire- place. Fabricate a hearth extension using a material which meets the following specifications: a layer of noncombustible, inorganic material having a thermal conductivity of K=0.84 BTU IN/FT, HR. F (or less) at 1" thick. For example, if the material selected has a K factor of 0.25, such as glass fiber, the following formula would apply:

0.25x 1.0" = 0.30" thickness required

Thermal conductivity "K" of materials can be obtained from the manufacturer or supplier of the noncombustible material. If the hearth extension is to be covered, use noncombustible material such as tile, slate, brick, concrete, metal, glass, marble, stone, etc. Provide a means to prevent the hearth extension from shifting and seal gap between the fireplace frame and hearth extension with a non- combustible material (see Figure 3).

MANTELS
A mantel may be installed if desired (see Figure
4). Woodwork such as wood trims, mantels or any
other combustible material projecting from the
front face must not be placed within 12" (JM36) or
18" (JM42/50) of the fireplace opening. Combus-
tible materials above 12" (JM36) or 18" (JM42/50)
and projecting more than 1 1/2" from the fireplace
must not be placed less than 15" (JM36) or 21"
(JM42/50) from the top opening of the fireplace
(NFPA STD 211, Sec. 7-3.3.3).
Mantels or any other combustible material also
may come up to the side edge of the black metal
face of the fireplace just as long as the projection
from the front face fall within the limit shown in
Figure 4.
	12		/4" Ref.	Combustible
		1		Material
				Safe
6"				Zone for
Ref.	33°			Projection of
				Combustible
	3" Nom.			Materials
15" Min.	1	/2" Max.
(JM36)
	1
21" Min.
(JM42/50)
12" Min. (JM36)				Upper
18" Min. (JM42/50)				Section of
				Fireplace

WARNING: Hearth extension

is to be installed only as shown

in Figure 3.

Seal Gap

Fireplace Front

Fireplace
Opening
Top View of Fireplace
7.75" (JM36)	FIREBOX
11.5" (JM42/50)

Ember Protector

Fireplace Front

Raised Hearth

Ember Protector

Fireplace Front

Elevated

Hearth

Extension

Seal Gap

3" Max.

SAFE ZONE

4.5"

33°

Min. to

Perpendicular

Side Wall

12" - JM36

18" - JM42/50

Figure 4 - Mantel Clearances to

Combustible Material

Ember Protector

Figure 3 - Hearth Extension

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