Vermont Casting 647 BFC - Manual (Page 16)

16
BFC36 Balance Flue Heat-Circulating Fireplace
7412647
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
Non-combustible 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.**
(CFM Corporation)
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.
Finish Glass Doors
The fallaway handles are used to open and close the
front doors. The fallaway handles may be removed
after each use or may be left in place. CAUTION: If the
handles are left in place during operation, they may
become hot. (Fig. 24)
Adjust door alignment by loosening the phillips head
screws which secure the door hinges to the door.
Adjusting one hinge while leaving the other tight will
serve to rotate the inner edge up or down. Adjusting
both hinges at the same time allows the door to adjust
side-to-side.
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Steel Handle
Fallaway
Handle
Fig. 24 Insert fallaway handle into steel handle.
FP1584