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17
M400BFC Balanced Flue Heat-Circulating Fireplace
87D1505
WARNING: Hearth extension must be installed in
accordance with Figure 23 and must not cover the
bottom front opening of the circulating model.
Alternate noncombustible materials may be used pro-
viding the (total) thermal resistance (Rt value) of the al-
ternate 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. 24)
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).
COMMON MATERIALS AND FACTORS
MATERIAL K*
R
MINIMUM
THICKNESS
EH2416
Common Brick
0.458
5.0
1.09 0.50 in.**
0.10 5.46 in.**
(MHSC)
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. 22 Hearth extension material factors.
Example of Determining Hearth Extension
Equivalents
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
materials with non-
combustible 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. 23 Sealing gaps.
KT108b
BFC
Correct door position
8/23/00 djt
Correct Wrong
Fig. 28 Correct door position.
KT108b
Glass Door Operation
The M400BFC is intended for use only with the doors
fully closed. (Fig. 28)