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Cwc series woodburning fireplace, Hearth installation, Minimum wall clearances – Monessen Hearth CWC500 User Manual

Page 15: Minimum hearth extension dimensions

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15

CWC Series Woodburning Fireplace

87D1504

1. Manville - CERAFORM 126, K=.27,
1/2 inches thick
2. MHSC - EH2416, K = .458,
1 inch thick required.

Hearth Installation

A hearth extension is required to protect a combustible
floor in front of the fireplace. Refer to Figure 24 for
minimum dimensions and mounting detail.
NOTe: Hearth extension must not cover the air
inlet/outlet opening of a fireplace.
The hearth extension described in Figure 24 must be a
durable noncombustible material with a minimum (to-
tal) Rt value of 1.09; refer to Figure 25 for examples.
The overall height (above a combustible floor), depth
and width must be as indicated, with the extension
centered to the fireplace opening.
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. 24)

Secure the hearth extension to the floor to prevent shift-
ing, 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. 22 and 26)
WARNINg: HeARTH eXTeNSION MUST be IN-
STALLeD IN ACCORDANCe WITH FIgURe 24 AND
MUST NOT COVeR THe bOTTOM FRONT OPeNINg
OF THe CIRCULATINg MODeL.
Alternate noncombustible materials may be used provid-
ing the (total) thermal resistance (Rt value) of the alter-
nate 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. Fac-
tors are related by the formula K = 1/R.
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).

Minimum Wall Clearances

WITH

Noncombustible

Surround Facing

WITHOUT

Noncombustible

Surround Facing

Minimum Hearth Extension Dimensions

(for On-Site Construction)

G

H

G

J

Seal cracks

between the

fireplace

and hearth

extension with

noncombustible

material

Safety strips

must overlap

56O

" minimum

May install

noncombustible

decorative

covering

OR .018" min.

sheet metal

FIREPLACE

HEARTH

COMBUSTIBLE

FLOOR

MINIMUM

INSULATION

VALUE "R"

4" MIN.

FP594A
WMC combustible min.
1/29/99 djt

FIREBOX

OPENING

A - Min. clearance

to combustible

perpendicular wall

B - Min. clearance

to combustible

perpendicular wall when

using noncombustible wall shield*

SIDE

WALL

SIDE

WALL

F**

C**

E

E

D

4" BRICK

(Example material)

Combustible material permitted within shaded area.

* Noncombustible wall shield requires 1" MHSC EH2416

insulation (minimum R Value = 1.85) between decorative

noncombustible rigid covering and combustible wall.

Minimum height and width is 40" x 40".
** Dimension/degree of angle will vary depending on thickness

of noncombustible surround facing.

4"

Shaded area starts

1/2" away from

edge of unit

FP594A

Fig. 24 Combustible side wall protection and hearth extension dimensions.

A

b

C

D

e

F

g

H

J

CWC400

16"

12"

48°

41°

18"

14"

7C\v"

16"

48"

406 mm 305 mm

457 mm 356 mm 197 mm 406 mm 1219 mm

CWC500

20"

12"

42°

35°

18"

14"

11Z\x"

20"

61Z\x"

508 mm 305 mm

457 mm 356 mm 292 mm 508 mm 1562 mm

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