Page 11
*When vent terminal is less than 10 feet (3m)
horizontally from a forced air inlet, the terminal
must be at least 3 feet (0.9m) above the air inlet.
(US only)
† A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.
‡ Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor.
Notes:
1) In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code.
2) In accordance with the current ANSI Z223.1/NFPA 54, Natural Fuel Gas Code.
3) If locally adopted installation codes specify clearances different than those illustrated, then the most stringent clearance shall prevail.
4) For clearances not specified in CAN/CSA-B149, clearance is in accordance with local installation codes and the requirements of the gas supplier.
5) For clearances not specified in ANSI Z223.1/ NFPA 54, clearance is in accordance with local installation codes and the requirements of the gas supplier.
6) IMPORTANT: Terminal must be placed such that it remains a minimum of 12” above maximum expected snow line. Local codes may have more specific
requirements, and must be consulted.
A = Clearance above grade, veranda, porch,
deck, or balcony
)
m
c
0
3
(
n
i
2
1
)
m
c
0
3
(
n
i
2
1
B = Clearance to window or door that may be
opened
●
6 in (15 cm) for appliances
≤
10,000 Btuh (3 kW)
●
12 in (30 cm) for appliances > 10,000 Btuh (3 kW) and
≤
100,000 Btuh (30 kW)
●
36 in (91 cm) for appliances >100,000 Btuh (30 kW)
●
6 in (15 cm) for appliances
≤
10,000 Btuh (3 kW)
●
9 in (23 cm) for appliances > 10,000 Btuh (3 kW) and
≤
50,000 Btuh (15 kW)
●
12 in (30 cm) for appliances >50,000 Btuh (15 kW)
w
o
d
n
i
w
d
e
s
o
l
c
y
lt
n
e
n
a
m
r
e
p
o
t
e
c
n
a
r
a
e
l
C
=
C
D = Vertical clearance to ventilated soffit located
above the terminal within a horizontal
distance of 2 ft (61 cm) from
the center line of the terminal
ti
ff
o
s
d
e
t
a
li
t
n
e
v
n
u
o
t
e
c
n
a
r
a
e
l
C
=
E
r
e
n
r
o
c
e
d
i
s
t
u
o
o
t
e
c
n
a
r
a
e
l
C
=
F
See Note 4
See Note 4
See Note 4
See Note 4
See Note 4
See Note 5
See Note 5
See Note 5
See Note 5
See Note 5
See Note 5
See Note 5
See Note 5
r
e
n
r
o
c
e
d
i
s
n
i
o
t
e
c
n
a
r
a
e
l
C
=
G
H = Clearance to each side of centerline
extended above meter / regulator assy
3 ft (91 cm) within a height of 15 ft (4.6 m)
)
m
c
1
9
(
tf
3
t
e
lt
u
o
t
n
e
v
r
o
t
a
l
u
g
e
r
e
c
i
v
r
e
s
o
t
e
c
n
a
r
a
e
l
C
=
I
J = Clearance to nonmechanical air
supply inlet to building or the
combustion air inlet to any
other appliance
●
6 in (15 cm) for appliances
≤
10,000 Btuh (3 kW)
●
12 in (30cm) for appliances > 10,000 Btuh (3 kW) and
≤
100,000 Btuh (30 kW)
●
36 in (91 cm) for appliances > 100,000 Btuh (30 kW)
●
6 in (15 cm) for appliances
≤
10,000 Btuh (3 kW)
●
9 in (23cm) for appliances > 10,000 Btuh (3 kW) and
≤
50,000 Btuh (15 kW)
●
12 in (30 cm) for appliances > 50,000 Btuh (15 kW)
K = Clearance to a mechanical air
supply inlet
n
i
h
ti
w
f
i
e
v
o
b
a
)
m
c
1
9
(
tf
3
)
m
3
8
.
1
(
tf
6
10 ft (3 m) horizontally
L = Clearance above paved sidewalk or paved
driveway located on public property
I
y
r
o
g
e
t
a
C
(
s
m
e
t
s
y
s
t
f
a
r
d
l
a
c
i
n
a
h
c
e
m
r
o
f
)
m
3
1
.
2
(
tf
7
†
)
m
3
1
.
2
(
tf
7
appliances). Vents for Category II and IV appliances
cannot be located above public walkways or other
areas where condensate or vapor can cause a nuisance
or hazard*
M = Clearance under veranda, porch, deck, or
balcony
‡
)
m
c
0
3
(
n
i
2
1
* The manufacturer shall specify a minimum clearance or state "Not applicable" in the table and/or instructions.
i) The minimum distance from adjacent public walkways, adjacent buildings, openable windows, and building
openings shall not be less than those values specified in the National Fule Gas Code, ANSI Z223.1/NFPA 54,
and/or the Natural Gas and Propane Installation Code, CSA B149.1;
ii) Information on preventing blockage by snow; and
iii) Information on protecting building materials from degradation by flue gases.
† A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single
family dwellings and serves both dwellings.
‡ Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor.
Notes:
1) In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code.
2) In accordance with the current ANSI Z223.1/NFPA 54, Natural Fuel Gas Code.
3) If locally adopted installation codes specify clearances different than those illustrated, then
the most stringent clearance shall prevail.
Canadian Installations1
U.S. Installations2
Figure 4. Vent Terminal Clearance.
Mighty Therm
2
(200, 300, 400) Install & Operating
