LG Electronics MP-42OD manual 21

Wall Shield Required

Where Less Than 12"

Hearth Extension Dimensions

24"

A

16"

B

35"

30"

C

8"

C

D

52"

B

C

C

Note: To convert inches to millimeters divide by .03937.

B

D

A

D

Figure 53

C

A

Methods of Determining Hearth Extension and Wall Shield

Listed Material

Equivalents - To determine the thickness required for the alternate

k (per inch)

r (per inch)

Listed Min.Thickness

material when either the "k" value or "r" value is known, use either the

1"

k formula or r formula.

Listed Material

.84

1.19

Example: If Micore 160 is to be used for the hearth extension fireplace,

KL

rL

T

L

** Approved

Alternate Materials for Floor/Hearth Protection

how thick must this material be?

kM = k value per inch of alternate material

AlternativeMaterials

Thermal Values

MinimumThickness

(rounded to nearest 1/8 inch)

rM = r value per inch of alternate material

k (per inch)

r (per inch)

Min. Thickness

TM =

minimum thickness required for alternate material

KM

rM

TM

Kaowool M Board

.47

2.13

.56" (1/2")

TS =

standard thickness of the alternate material

Micore 160™

.35

2.86

.42" (3/8")

kL = k value per inch of listed material

U.S. Gypsum

rL = r value per inch of listed material

Micore 300™

.46

2.17

.55" (1/2")

TL = minimum thickness of listed material

U.S. Gypsum

Note: An asterix "*" indicates, it is a value taken from Table 5.

Durock™ Cement Board

1.92

.52

2.29" (2-1/4")

U.S. Gypsum

Using the k formula:

Hardibacker™

1.95

.513

2.32" (2-3/8")

Minimum

k-value (per Inch) of

Specified min.

Hardibacker 500™

2.30

.435

2.74" (2-3/4")

thickness of

=

alternate material (kM)

x

thickness

Cultered Stone Hearth-

2.82

.355

3.36" (3-3/8")

alternate

k-value (per inch)

of listed

stone™

material (TM)

of listed material (kL)

material (TL)

Wonderboard

3.23

.31

3.85" (3-7/8")

TM (inches)

=

kM

x

TL

Super Firetemp M

.61

1.64

.73" (3/4")

Johns-Manville

*.84

Super Firetemp L

.54

1.85

.64" (5/8")

TM (inches)

=

*.35

x

1"

Johns-Manville

Face brick

9.00

.111

10.71" (10-3/4")

*.84

Common brick

5.00

.20

5.95" (6")

.416 (inches)=

.416

x

1"

Cement mortar

5.00

.20

5.95" (6")

Answer - The minimum required thickness of the Micore 160 is .417," there-

Ceramic tile

12.5

.08

14.88" (14-7/8")

fore round up to nearest standard thickness available which is 1/2."

Marble

~11

~.09

13.10" (13-1/8")

Using the r formula:

Table 5

Minimum

r-value (per Inch)

Specified min.

** If the hearth extension

material(s) that is intended to be used is NOT listed

thickness of

=

of listed material

x

thickness

on Table 5, the material

can still be used if the material(s) is noncombustible.

alternate

r-value (per inch)

of listed

However, the manufacturer

of the material must provide either the listed k-value

material

of alternate material

material

per inch or r-value per inch with listed thickness so that the minimum thickness

required for the hearth can be calculated (per instructions on this Page and/or

TM (inches)

=

rL

x

T

as specified in the NFI Certification manuals).

Note: Also see NFI (National Fireplace Institute) Certification Manuals showing

L

rM

other exceptable caluculation methods and acceptable alternate materials

which can be used.

TM (inches)

=

*1.19

x

1"

* 2.86

.417 (inches)=

.416

x

1"

Answer - The minimum required thickness of the Micore 160 is .417," there-

fore round up to nearest standard thickness available which is 1/2."

21

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.