Vermont Castings MLDV500 Installation & Operating Instructions Manual page 18

MLDV Series Gas Fireplace
The horizontal vent run refers to the total length of vent
pipe from the flue collar of the fireplace (or the top of the
Transition Elbow) to the face of the finished outside wall
or the mounting flange of the termination.
•
The maximum number of 90° elbows per side wall
installation is three (3). Figure 20
•
If a 90° elbow is fitted directly on the top of the fireplace,
the maximum horizontal vent run before the termination
or a vertical rise is 36" (914 mm). Figure 21
3 x 90°
Elbows
Figure 20 -
Maximum Three (3) 90° Elbows
Per Installation
36"
FP1176
(914 mm)
Max.
max 90 bends
FP1177
Figure 21 -
Maximum Horizontal Run with No Rise
When installing the appliance as a rear
vent unit, the 90° or 45° transition elbow
attached directly to the rear of the unit is
NOT INCLUDED in the following criteria
and calculations and, unless specifically
mentioned, should be ignored when
calculating venting layouts.
18
3 x 90°
Elbows
(914 mm)
Max 20"
•
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).
FP1176
FP1958
36"
Max.
Figure 22 -
Horizontal Run Reduction
FP1958
Horizontal run reduction
7'6"
FP1959
VENTING INSTALLATION
90°
A
7'6"
A
10'
Horizontal 90° Elbow = 3' Reduction
A + B = 17' Maximum
Figure 23 -
Maximum Vent Run with Elbows
B
B
7'
75D0004