Demand Duo
™
R
-
Series Installation and Operation Manual
19
All flue (vent) gases must be directed to the
outdoors of the building or structure and must not
terminate horizontally.
Roof pitch is x/12
H (minimum) –
Minimum height from
roof to lowest
discharge opening
Roof Slope
H (minimum)
ft
m
Flat to 6/12
1.0
0.30
Over 6/12 to 7/12
1.25
0.38
Over 7/12 to 8/12
1.5
0.46
Over 8/12 to 9/12
2.0
0.61
Over 9/12 to 10/12
2.5
0.76
Over 10/12 to 11/12
3.25
0.99
Over 11/12 to 12/12
4.0
1.22
Over 12/12 to 14/12
5.0
1.52
Over 14/12 to 16/12
6.0
1.83
Over 16/12 to 18/12
7.0
2.13
Over 18/12 to 20/12
7.5
2.27
Over 20/12 to 21/12
8.0
2.44
The vent termination shall comply with the
following requirements:
If the gas vent is 12 in. (300 mm) or less in diam-
eter and located not less than 8 ft. (2.4 m) from a
vertical wall or similar obstruction, the
termination must comply with the requirements
stated in Table 4 and Figure 9. If the gas vent is
greater than 12 inches in diameter or located less
than 8 ft. (2.4 m) from a vertical wall or similar
obstruction, the termination must end at a mini-
mum of 2 ft. (0.6 m) above any portion of a build-
ing within 10 ft. (3.0 m) horizontally.
B
-
Vent type gas vent shall terminate at least 5 ft.
(1.5 m) in vertical height above the highest
connected appliance draft hood or flue collar.
Decorative shrouds or coverings shall not be
installed over the gas vent termination unless
listed for use with the specific gas vent and are
installed in accordance with the manufacturer
’
s
installation instructions.
All gas vents shall extend through the roof
flashing, roof jack, or roof thimble and terminate
with a listed cap or listed roof assembly.
The gas vent shall terminate at least 3 ft. (0.9 m)
above any forced air inlet located within 10 ft.
(3.0 m).
Listed
Gas vent
Listed
Cap
Lowest discharge opening
12
x
Table 4
Figure 9
Example: X = 6, Roof Slope = 6/12, H (Minimum
1.25 ft. (0.38))
