Vermont Castings BC36MH Installation & Operating Manual page 14

BC36MH, BC42MH Woodburning Fireplace
1 "
Ref.
*12" from top of grille opening for circulating
models
**3" from top of grille opening for circulating
models
Fig. 21 Combustible mantel clearances.
Hearth Installation
A hearth extension is required to protect a combustible
floor in front of the fireplace. Refer to Figure 22 for mini-
mum dimension and mounting detail.
NOTE: Hearth Extension must not cover the air
inlet/outlet opening of a fireplace.
The hearth extension described in Figure 22 must be a
durable noncombustible material with a minimum (total)
Rt value of 1.09; refer to Figure 23 for examples. The
overall height (above a combustible floor), depth and
width must be a 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. 22)
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 fireplace
hearth and hearth extension with a noncombustible
material. (Fig. 22 and 24)
14
*
**
Combustible materials are
permitted within a shaded area
shown in Figure 22 titled
Minimum Wall Clearances.
WARNING: Hearth extension must be installed in
accordance with Figure 24 and must not cover the
bottom front opening of the fireplace.
MA81
Alternate noncombustible materials may be used
rev. 8/5/97
providing the (total) thermal resistance (Rt value) of the
alternate material employed is greater than or equal to
R = 1.09. Thermal resistance (R) or thermal conductiv-
ity (K), may be obtained from manufacturer of material.
Factors 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).
Face Plate
MA81
7412972