58 Venting for Combustion Air
Terminal Clearances for Direct Vent Installations
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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
0 in (0 cm)
5
0 in (0 cm)
5
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
Equal or greater than
soffit depth
4, 5
Equal or greater than
soffit depth
4, 5
E
Clearance to unventilated soffit
Equal or greater than
soffit depth
4, 5
Equal or greater than
soffit depth
4, 5
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*
* 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.
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
3 If locally adopted installation codes specify clearances different than those illustrated, then the most stringent clearance shall prevail.
4 Soffit with 12” depth requires a minimum of 12” vertical clearance from the termination (36” soffit requires a minimum of 36”
vertical clearance)
5 In the areas where corrosion and discoloration of building materials can occur, a minimum clearance of 12” shall apply.
† 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.
Direct exhaust vapors and condensate away from building materials to avoid degradation. 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 Fuel Gas Code, ANSI Z223.1/NFPA 54, and/or the Natural Gas and Propane Installation Code, CSA B149.1.
