WMC Series Woodburning Fireplace
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 shifting, using trim molding or other similar means at three (3) outer edges. Seal crack between the fire- place hearth and hearth extension with a noncombus- tible 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 |
| WITHOUT | |
Noncombustible |
| Noncombustible | |
Surround Facing |
| Surround Facing | |
|
| Shaded area starts | |
4" BRICK |
| 1/2" away from | |
(Example material) |
| edge of unit | |
|
| 4" | |
E F** | FIREBOX | E | |
| OPENING | D | |
C** | A - Min. clearance | ||
| |||
| to combustible |
| |
SIDE | perpendicular wall |
| |
B - Min. clearance | SIDE | ||
WALL | to combustible | WALL | |
| perpendicular wall when | ||
| using noncombustible wall shield* | ||
Combustible material permitted within shaded area.
*Noncombustible wall shield requires 1" Majestic 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.
Minimum Hearth Extension Dimensions
(for
| H | G | G |
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| |
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| J |
| Seal cracks |
|
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May install | between the |
| |
noncombustible | fireplace |
|
|
decorative | and hearth |
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covering | extension with |
| |
OR .018" min. | noncombustible |
| |
sheet metal | material |
| FIREPLACE |
|
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| HEARTH |
4" MIN. |
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|
|
COMBUSTIBLE | MINIMUM | Safety strips | |
FLOOR | INSULATION | must overlap | |
| VALUE "R" | ���" minimum | |
|
| A | B | C | D | E | F | G | H | J |
|
| WMC36 | 16" | 12" | 48° | 41° | 18" | 14" | 7³⁄₄" | 16" | 48" |
|
|
| 406 mm | 305 mm |
|
| 457 mm | 356 mm | 197 mm | 406 mm | 1219 mm |
|
| WMC42 | 20" | 12" | 42° | 35° | 18" | 14" | 11¹⁄₂" | 20" | 61¹⁄₂" |
|
|
| 508 mm | 305 mm |
|
| 457 mm | 356 mm | 292 mm | 508 mm | 1562 mm | FP594A |
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Fig. 24 Combustible side wall protection and hearth extension dimensions.
20000583 | 15 |