Valor MADRONA MF28JN Installation & Owner's Manual page 23

How to Read the Venting Chart
The chart below applies to top or rear outlet, roof or
wall termination with a vertical rise.
All rear outlet venting without a vertical rise must
be terminated by a snorkel.
1. The total length of the vent pipe cannot exceed 40
feet (12.2 m).
2. The minimum vertical height with roof termination is 8
feet (2.45 m).
3. Any combination of rise and run can be used as long
as they are within the allowable limits shown on the
chart below.
1" clearance
to combustible
around vertical
pipe
Example 1
V Value = V1 (6') + V2 (6') + V3 (2')= 14'
H Value = H1 (3') + H2 (3') = 6'
Not to scale
75% restrictor required
Venting
3" clearance
to combustible
above horizon-
tal pipe
1" clearance
to combustible
at bottom and
sides of hori-
zontal pipe
4. A maximum of 5 x 90 degrees elbows or equivalent (2
x 45 degrees = 90 degrees) can be used.
5. Each 90 degrees elbow installed on the horizontal
plane is equivalent to a 3 feet horizontal pipe;
therefore, 3 feet must be subtracted from allowable
horizontal run.(45 degrees elbow is equivalent to 18
inches horizontal pipe.)
6. All horizontal pipe runs must be graded 1/4 inch per
foot upwards in the direction of the exhaust fl ow.
7. Co-linear rear venting in existing chimney systems
is limited to 40 feet vertical rise.
8. Restrictors are not required for co-linear
installations.
Roof termination
V3
Wall termination
5 x 90º ELBOWS
40
Allowable Vent
38
Confi gurations
36
34
32
30
28
26
24
Restrictor 75
22
20
Example 1
18
16
14
12
10
8
6
4
2
2 4 6
HORIZONTAL RUN (ft)
QUALIFIED
INSTALLER
MAXIMUM
NO INSTALLA-
TION
Restrictor 50
NO INSTALLATION
8 10 12 14 16 18 20
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