MHSC DIRECT VENT MLDV500 Installation And Operating Instructions Manual page 19

VENTING INSTALLATION
HORIZONTAL (THROUGH-THE-WALL) TERMI-
NATION CONFIGURATION (continued)
•
If a 90° elbow is used in the horizontal vent run (level height
maintained) the horizontal vent length is reduced by 36".
Figure 23. This does not apply if the 90° elbows are used to
increase or redirect a vertical rise. Figure 22
Example: According to the vent graph (Page 17) the maximum
horizontal vent length in a system with a 7.5' vertical rise is 20'
(6 m) and if a 90° elbow is required in the horizontal vent it must
be reduced to 17' (5.2 m).
In Figures 22 and 23 dimension A plus B must not be greater
than 17' (5. m).
•
The maximum number of 45° elbows permitted per side wall
installation is two (). These elbows can be installed in either
the vertical or horizontal run.
•
For each 45° elbow installed in the horizontal run, 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.
•
The maximum number of elbow degrees in a system is 70°.
Figure 24
A
10'
Horizontal 90° Elbow = 3' Reduction
7'6"
A + B = 17' Maximum
FP1959
Figure 23 -
Maximum Vent Run with Elbows
75D0004
FP1958
Figure 22 -
Horizontal Run Reduction
B Example:
7'
FP1958
Horizontal run reduction
Total Angular Variation =
1
2
3
4
MLDV Series Gas Fireplace
90°
A
7'6"
Elbow 1 =
Elbow  =
Elbow 3 =
Elbow 4 =
1
2
3
4
1 +  + 3 + 4 = 70°
Figure 24 -
Maximum Elbow Usage
B
90°
45°
45°
90°
70°
FP1180
19