Hearthstone Quality Home Heating Products, Inc
® Green Mountain Insert 70 (Model 8450)
11
To determine the need to add floor protection (D)
beyond the hearth extension, do the following
calculation using the data in following table: D = B -
(A - C).
The standard configuration of the insert leaves no
projection of the convection air jacket in front of the
fireplace opening. Therefore, the minimum
projection is 0''. Although it is possible to position
the insert to obtain a projection of 2'' (51 mm) or 4''
(102 mm) of the convection air jacket in front of the
fireplace opening with the use of the surround
extension. The choice of the configuration will
depend on the previous installation instructions and
compliance with building code.
If the value (D) is negative or zero, additional floor
protection in front of the unit is not needed because
the masonry fireplace hearth extension is large
enough. If the value (D) is positive, an additional
floor protection in front of the hearth extension at
least equivalent to the result (D) must be added.
Maximum
Extended
Minimum
Extended
A
Dimensions of
the hearth
extension
Dimensions of the
hearth extension
B
See the following
sections
See the following
sections
C
2" / 4"
(51 / 102 mm)
0"
(0 mm )
D
D=B-(A-C)
D=B-(A-C)
E
10" / 12"
(254 / 305 mm)
14"
(356 m m )
Air
Jacket
Back from
fireplace facing
2" or 4"
Flush with
fireplace facing
Figure 5
– Floor Protection
I
NSTALLATION
R
AISED
5”
OR
L
ESS
If non-combustible material floor protection needs to
be added in front of and level with the hearth
extension of the masonry fireplace (F = 5" or less),
an R-value equal to or greater than 1.00 is required
and should extend at least 23" (584 mm) in front of
the unit (B).
Figure 6
– Installation 5” or Less
I
NSTALLATION
R
AISED
M
ORE
T
HAN
5”
If the extension of the masonry hearth is raised
more than 5" (127 mm) from the floor protection, a
non-combustible material, without an R-value, must
extend at least 16" (406 mm in USA) or 18" (457
mm in Canada) in front of the unit.
