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DVHVAC36
10001195
It is always best to locate the fireplace in such a way
that minimizes the number of offsets and horizontal vent
length.
The horizontal vent run refers to the total length of vent
pipe from the flue collar of the fireplace to the face of
the outer wall.
Horizontal plane means no vertical rise exists on this
portion of the vent assembly.
For some installations, it may be desirable to have
some amount of the horizontal vent run immediately
after the fireplace. A vertical rise must be used but can
be located anywhere in the vent system, to meet the
parameters identified in the venting graph.
• The maximum horizontal vent run is 20' (6 m) when
the vertical vent rise is 7¹⁄₂' (2.3 m). (Fig. 18)
1
2
3
4
1 + 2 + 3 + 4 = 270
o
CFM132
Insert Rear Vent Sidewall
2/26/01 sta
Sample:
Elbow 1 = 90°
Elbow 2 = 45°
Elbow 3 = 45°
Elbow 4 = 90°
Total angular variation = 270°
CFM132
Fig. 21 Maximum number of elbows.
B
7'
(2.1m)
V584-201
Horizontal Run
2/99 djt
A
10'
(3m)
7' 6"
(2.3m)
CFM147
Fig. 20 Maximum vent run with elbows.
A + B = 17' (5.2m) Max.
• The maximum number of 90° elbows per side wall
installation is three (3).
• The maximum number of 45° elbows permitted per
side wall installation is two (2). These elbows can be
installed in either the vertical or horizontal run.
• When one (1) 90° elbow is installed directly onto
another off the back of the fireplace the maximum
horizontal vent length is 36" (914 mm). (Fig. 19)
• For each 45° elbow installed in the horizontal run
(while maintaining a constant horizontal plane), the
length of the horizontal run MUST be reduced by 18"
(457 mm). This does not apply if the 45° elbows are
installed on the vertical part of the vent system.
• If a 90° elbow is used in the horizontal vent run
(level height maintained) the maximum horizontal
vent length is reduced by 36" (914 mm) (Fig. 20)
This does not apply if the 90° elbows are used to
increase or redirect a vertical rise.
CFM141
2/2/01 sta
Maximum
20 ft. (6.1m)
7.5'
(2.3m)
7TDVRT90
Elbow
15 ft.
(4.6m)
48"
(1.2m)
12"
(305mm)
Vertical Dimen-
sion 7¹⁄₂' (2.3m)
Minimum when
Horizontal Run is
20' (6m)
CFM141
Fig. 18 Maximum number of 90° elbows is three.
Example: According to the vent chart the maximum
horizontal vent length is 20' (6 m) when the vertical
height is 7.5' (2.3 m) from fireplace base height. If
one (1) 90° elbow is required in the horizontal vent, it
must be reduced to 17' (5.2 m).
• The maximum number of elbow degrees in a sys-
tem is 270°. (This does not include transition elbow
from rear vent to vertical vent.) (Fig. 21)
Maximum
3' (914mm)
7TDVRT90
Elbow
CFM142
Venting
2/2/01 sta
CFM142
Fig. 19 Maximum horizontal vent run with 90° elbows directly
off back of unit.