Hearth and Home Technologies ST42A owner manual Finishing, Hearth Extension

High temperature

(300°F min.) continuous,

HX3 or HX4

non-combustible sealant

Fireplace

non-combustible material

Protective

insulation

Hearth Ext

Tile, stone or other

or equivilent

(see Table below)

Metal Hearth

Strip

2 in. (51 mm)

Floor constructed of wood or

required

1 in. (25 mm) overlap

other combustible material

Figure 8.1 Hearth Extension Construction

Metal strips are placed 2 in. (51 mm) under the

front of the fireplace and must extend beyond the

WARNING

front and sides of fireplace by 2 in. (51 mm).

Figure 8.2 Positioning the Protective Metal Hearth Strips

Fire Risk

• Metal hearth strips MUST be installed.

WARNING

Sparks or embers may ignite fl ooring.

This fi replace has been tested and approved for use with a

Fire Risk

• Hearth extensions must be installed

hearth extension insulated to a minimum R value of 1.16.

exactly as specifi ed.

To substitute materials for the factory-available hearth ex-

High temperatures or hot embers may ignite

tensions, see Figure 8.3 and calculate insulation alternatives

concealed combustibles.

as per Table 8.1 and the following formulas:

Table 8.1

A

B

C

Hearth Extension Insulation Alternatives, R Value = 1.16

Minimum

k per inch

r per inch

thickness

Model #

A

B

C

Material

thick

thick

required

Hearth & Home HX3, HX4

0.43

2.33

1/2 in.

HX4

in.

66

20

12

USG Micore 300™

0.46

2.18

1/2 in.

mm

1676

508

305

USG Durock™ Cement Board

1.92

0.52

2-1/4 in.

Cement Mortar

5.0

0.20

5-7/8 in.

Common Brick

5.0

0.20

5-7/8 in.

Figure 8.3 Hearth Extension Dimensions

Ceramic Tile

12.50

0.08

14-5/8 in.

Armstrong™ Privacy Guard Plus

.046

2.18

1/2 in.

Marble

14.3-20.0

0.07-0.05

16-5/8 in. - 23-3/8 in.

24

Heatilator • ST42A • 35038 Rev G • 02/05