16
BFC36 Balanced Flue Heat-Circulating Fireplace
7412647
cordance with Figure 22 and must not cover the bottom
front opening of the circulating model.
Alternate noncombustible materials may be used 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 conductivity (K), may be
obtained from manufacturer of the material. Factors are
related by the formula K = 1/R. (Fig. 21)
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 resistance (Rt).
COMMON MATERIALS AND FACTORS
MATERIAL
K*
R
MINIMUM
THICKNESS
EH2416
Micor 300
Common Brick
0.458
5.0
1.09 0.50 in.**
0.10 5.46 in.**
R Value is for 1/2 inch.
* Units of K = BTU/SQ FT/HR
/˚F/IN
** Thickness of Listed Material
FP533ADD
Addendum
6/1/99 djt
8/4/99 changed .2 to .1
one inch to 1/2 inch djt
FP533ADD
Fig. 21
Hearth extension material factors.
Example of Determining Hearth Extension Equiva-
lents
To determine the thickness required for any
new
mate-
rial:
NEW
K of new material (per inch)
thickness
required
= --------------------------------------- X of listed
thickness
K of listed material (per inch) material
Example for Common Brick
T (new) = 5.0/0.458 x 0.50 in. =
5.46 in.
(new required
thickness).
FP550
BR/BC - SEALING
DETAILS
9/29/97
Wall Covering
Noncombustible
Decorative Fac-
ing
Seal all cracks
between fireplace
surround and wall ma-
terials with noncom-
bustible material.
Noncombus-
tible Decorative
Covering
Hearth Exten-
sion Insulation
2 x 4” Header
- Do not notch at
standoffs
Seal crack between
fireplace and hearth
extension with noncom-
bustible material
Safety Strips -
Must be overlapped 1/2”
minimum
Side View
FP550
Fig. 22
Sealing gaps.
KT108b
BFC
Correct door position
8/23/00 djt
Correct
Wrong
Fig. 23
Correct door position.
KT108b
Glass Door Operation
The BFC36 is intended for use only with the doors fully
closed. (Fig. 23)