Hearth and Home Technologies A42R, A36RH Finishing, Hearth Extension, = 1/k x inches of thickness

11 Finishing

A. Non-Combustible Materials

•Materials which will not ignite and burn, composed of any combination of the following:

-	Steel	-	Iron
-	Brick	-	Tile
-	Concrete	-	Slate
-	Glass	-	Plasters

•Materials reported as passing ASTM E 136, Standard

Test Method for Behavior of Metals, in a Vertical Tube Furnace at 750° C

B. Combustible Materials

•Materials made of or surfaced with any of the following materials:

-	Wood	-	Compressed paper
-	Plant fibers	-	Plastic

•Any material that can ignite and burn; flame proofed or not, plastered or un-plastered

C. Hearth Extension

WARNING! Risk of fire! High temperatures, sparks, embers or other burning material falling from the fireplace may ignite flooring or concealed combustible surfaces.

•Protective metal hearth strips MUST be installed (Section 7.C.).

•Hearth extensions MUST be installed exactly as specified.

Table 11.1

R = 1/k x inches of thickness

Table 11.2

•You MUST use a hearth extension with this fireplace.

•This fireplace has been tested and approved for use with a hearth extension insulated to a minimum R value of 1.03.

•The hearth extension material MUST be covered with tile, stone or other non-combustible material.

•Manufactured hearth materials will usually have a published R value (resistance to heat) or k value (conductivity of heat). Refer to the formula in Table 11.1 to convert a k value to an R value,

•Refer to Table 11.2 for hearth extension insulation alternatives.

C

A

C

D

Hearth Extension Dimensions

Model #		A	B	C
A36	in.	52	16	8
(HX3)	mm	1321	406	203
A42	in.	66	20	8
(HX4)	mm	1676	508	203

Figure 11.1 Hearth Extension Dimensions

Hearth Extension Insulation Alternatives-Total minimum R Value must equal 1.03

			Minimum
	k per inch	r per inch	thickness
Material	thick	thick	required
Hearth & Home HX3, HX4 (Micore 300™)	0.49	2.06	1/2 in.
USG Micore 160™	0.39	2.54	1/2 in.
USG Durock™ Cement Board	1.92	0.52	2 in.
Cement Mortor	5.0	0.20	5-1/8 in.
Common Brick	5.0	0.20	5-1/8 in.
Ceramic Tile	12.50	0.08	12-1/4 in.
Armstrong™ Privacy Guard Plus	0.46	2.18	1/2 in.
Marble	14.3-20.0	0.07-0.05	14-5/8 in. - 20-3/8 in.

Heatilator • A36R & A42R • 28376 • Rev AF • 11/08 37