Vermont Castings MLDV500 Installation & Operating Instructions Manual page 19

VENTING INSTALLATION
•
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
Example: Elbow 1 =
Elbow  =
Elbow 3 =
Elbow 4 =
Total Angular Variation =
1
2
3
4
1 +  + 3 + 4 = 70°
Figure 24 -
Maximum Elbow Usage
HORIZONTAL WITH VERTICAL RISE
(THROUGH-THE-WALL) APPLICATIONS
1. Locate and cut the vent opening in the wall. For
combustible walls first frame in opening.
Combustible Interior Walls: Cut a 1
hole through the interior wall.
Combustible Exterior Walls: Cut a 10
square hole through the exterior wall frame. Figure 25
Noncombustible Walls: Hole opening should be 8
(16 mm) in diameter.
. The center of the hole should line up with the center line
of the horizontal rigid vent pipe end. Allow 1/4" minimum
rise per foot. Figure 25
NOTE: #1222DA reducer must be used when 4x6B\,"
venting is preferred. The 7TDVP58 reducer must be
used when 4" x 7" venting is preferred. Reducer must
be installed directly onto unit at the fireplace collar
before vertical rise.
75D0004
90°
45°
45°
90°
70°
1
2
3
4
FP1180
"H x 10 " W
Z\x Z\x
"H x 10
Z\x Z\x
(67 mm
10 1 / "

)
(67 mm
Combustible
1
8 / "

)
(16 mm
Noncombustible
Figure 25 -
Exterior Wall Framing Dimensions for 5" x 8"
FP1954
wall framing
You may use a reducer from 5" x 8" to 4" x
6B\," or 4" x 7" for horizontal with vertical rise
applications. ONLY use framing instructions
below when using 4" x 6B\," or 4" x 7"
venting.
If the reducer is installed at the rear of the
unit, you must immediately follow with a 90
elbow for a vertical rise before continuing
with any horizontal run. There is a minimum
total height of 7 feet from the fireplace floor
to the last section of pipe before horizontal
run. Refer to graph on Page 17.
1. Locate and cut the vent opening in the wall. For com-
bustible walls first frame in opening.
Combustible Interior Walls: Cut a 11Z\x"H x 9Z\x" W
hole through the interior wall.
"W
Combustible Exterior Walls: Cut a 9Z\x"H x 9Z\x"W
square hole through the exterior wall frame. Figure 26
" Noncombustible Walls: Hole opening should be 7Z\x"
Z\x
(190 mm) in diameter.
. The center of the hole should line up with the center line
of the horizontal rigid vent pipe end. Allow 1/4" minimum
rise per foot. Figure 26
MLDV Series Gas Fireplace
1
10 / "

)
Wall
Wall
FP1954
19