33
At
least
36
in.
18
in.
ma
x
imum
Vertical
separation
between
combustion
air
and
vent
8
3/4
in.
(222mm)for
3
in.
(76mm)
k
i t
6
3/4
in.
(172mm)for
2
in.
(51mm)
k
i t
Roof
Te rmination
(Preferred)
Abandoned
masonry
used
as
raceway
(per
code)
At
least
36
in.
A
Maintain
12
in.
min.
clearance
above
highest
anticipated
snow
level,
ma
x
imum
of
24
in.
above
roof
Concentric
Vent
and
Combustion
Air
Roof
Termination
(preferred)
1
in.
(25mm)
ma
x
imum
(typ)
from
wall
to
inlet
12
in.
(305mm)
minimum
from
overhang
or
roof
Maintain
12
in.
min.
clearance
above
highest
anticipated
snow
level
or
grade
whichever
is
greater
A
At
lea
st
36
in.
Concentric
Vent
and
Combustion
-
Air
Side
Te rmination
A
At
least
36
in.
Side
wall
termination
of
less
than
12
in.
(305mm)
above
highest
snow
level
12
in.
min
from
overhang
or
roof
12
in.
(305mm)
separation
between
bottom
ofcombustion
air
and
bottom
of
vent
(typ)
Maintain
12
in.
min.
clearance
above
highest
anticipated
snow
level
or
grade
whichever
is
greater
(typ)
A
At
least
36
in.
A
Maintain
12
in.
(305mm)min
.
clearance
above
highest
anticipated
snow
level
Ma
x
imum
of
24
in.(614mm)
above
roof
90
°
N
ote
:
"A"
denotes
0
to
<
2
in.
Between
the
first
2
vents
Third
vent
must
be
>
36
in.
away
(typ)
(914mm
)
(305mm)
(914mm)
(305mm)
(305mm)
(914mm)
(914mm)
(457mm)
(51mm)
(914mm)
A05090
Fig. 36 -- Combustion Air and Vent Termination for Direct Vent (2--pipe) System
Abandoned
masonry
used
as
raceway
(per
code)
12
in.
(305
mm)
min.
from
overhang
or
roof
Maintain
12
in.
(305mm)
minimum
clearance
above
highest
anticipated
snow
level
or
grade
whichever
is
greater.
Side
wall
termination
with
2
elbows
(preferred)
12
in.
min.
(305
mm)from
overhang
or
roof
Maintain
12
in.
(305mm)
minimum
clearance
above
highest
anticipated
snow
level
or
grade
whichever
is
greater
6
in.
(152mm)
minimum
clearance
between
wall
and
end
of
vent
pipe.
10
in.
(254mm)
ma
x
imum
pipe
length
Sidewall
Termination
with
Straight
Pipe
(preferred)
Roof
Termination
(Preferred)
Vent
Maintain
12
in
.
minimum
clearance
above
highest
anticipated
snow
level
ma
x
imum
of
24
in.
(610mm)
above
roof
.
90
°
(305mm)
A05091
Fig. 37 -- Vent Pipe Termination for Ventilated Combustion Air System
355C
A
V