88 Installing a Common Vent System
Direct Venting
Ref Description
Canadian Direct
Vent Installations
1
US Direct Vent
Installations
2
A
Clearance above grade, veranda, porch, deck, or
balcony
12 in (30 cm)
12 in (30 cm)
B
Clearance to window or door that may be opened
36 in (91 cm)
12 in (30 cm)
C
Clearance to permanently closed window
12 in (30 cm)*
12 in (30 cm)*
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
3 ft (91 cm)*
3 ft (91 cm)*
E
Clearance to unventilated soffit
3 ft (91 cm)*
3 ft (91 cm)*
F
Clearance to outside corner
2 ft (61 cm)*
2 ft (61 cm)*
G
Clearance to inside corner
12 in (30 cm)*
12 in (30 cm)*
H
Clearance to each side of center line extended above
meter/regulator assembly
3 ft (91 cm) within a
height 15 ft above
the meter/regulator
assembly
3 ft (91 cm) within a
height of 15 ft (4.6 m)*
I
Clearance to service regulator vent outlet
3 ft (91 cm)
3 ft (91 cm)*
J
Clearance to nonmechanical air supply inlet to building
or the combustion air inlet to any other appliance
36 in (91 cm)
12 in (30 cm)
K
Clearance to a mechanical air supply inlet
6 ft (1.83 m)
3 ft (91 cm) above
if within 10 ft (3 m)
horizontally
L
Clearance above paved sidewalk or paved driveway
located on public property
7 ft (2.13 m)
†
7 ft (2.13 m)
†
M
Clearance under veranda, porch deck, or balcony
12 in (30 cm)
‡
12 in (30 cm) - open
on 3 sides*
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 National Fuel Gas Code
† 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.
* Suggested clearances by the manufacturer. If the clearances required by local codes are different from those from the table
above, the greater clearance should apply.
