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Vermont Castings, Majestic Products DVRT36/39/43
10002428
It is very important the venting system maintain its
balance between the combustion air intake and the
flue gas exhaust, therefore, certain limitations as to
vent configurations apply and must be strictly
adhered to.
The Vent Graph (Page 14), showing the relationship
between vertical and horizontal side wall venting, will
help to determine the various dimensions allowable.
Minimum clearance between vent pipes and com-
bustible materials is 1” (25mm) on top, bottom and
sides unless otherwise noted.
When vent termination exits through foundations less
than 20” (508mm) below siding outcrop, the vent pipe
must flush up with the siding.
It is best to position the fireplace so the number of
offsets and horizontal vent length are minimized.
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 outer wall.
Horizontal plane means no vertical rise exists on this
portion of the vent assembly.
Vertical Sidewall Application
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, are to be ignored when
calculating venting layouts.
• If a 90° elbow is used in the horizontal vent run
(level height maintained), the horizontal vent length
is reduced by 36” (914 mm). (Fig. 25a and
Fig. 25b) This does not apply if the 90° elbow is
used to increase or redirect a vertical rise. (Fig. 25b)
Example: According to the Vent Graph (Page 14), the
maximum horizontal vent length in a system with a 7.5’
(2.3m) vertical rise is 20’ (6m) and if a 90° elbow is
required in the horizontal vent it must be reduced to 17’
(5.2m).
7’6"
A
B
90
o
A + B = 17’ (Max.)
FP1178
Fig. 25a Horizontal run reduction.
3 x 90°
Elbows
FP1176
Fig. 23 Maximum three (3) 90° elbows per installation.
3 x 90°
Elbows
• The maximum number of 90˚ elbows per side wall
installation is three (3). (Fig. 23)
• If a 90˚ elbow is fitted directly on top of the fireplace
flange, the maximum horizontal vent run before the
termination or a vertical rise is 36 in. (914mm). (Fig.
24)
36"
(914mm)
Max.
FP1177
Fig. 24 Maximum horizontal run with no rise.
36"
(914mm)
Max.
Finished
Wall
These ends screwed
to appliance.
These ends
should be even.
FP1005
Fig. 22 Flat to the wall installation.
Vent
Termination