38 Installing the Water Heater
3.5.2 Maintaining Clearances
Terminal clearances
Maintain the following venting clearances, as required by
ANSI Z21.10.3 and the National Fuel Gas Code, ANSI
Z223.1/NFPA 54
:
Inside
corner detail
Operable
Operable
Legend:
Fixed
closed
Fixed
closed
Vent terminal
Air supply inlet
Area where terminal is not permitted
Regulator vent outlet In
the event no regulator
is present, H and I can
be disregarded.
For indoor models (direct vent)
Ref Description
Direct Vent Installations
1
A
Clearance above grade, veranda, porch, deck, or balcony
12 in (30 cm)
B
Clearance to window or door that may be opened
12 in (30 cm)
C
Clearance to permanently closed window
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)*
E
Clearance to unventilated soffit
3 ft (91 cm)*
F
Clearance to outside corner
2 ft (61 cm)*
G
Clearance to inside corner
12 in (30 cm)*
H
Clearance to each side of center line extended above 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)*
J
Clearance to nonmechanical air supply inlet to building or the
combustion air inlet to any other appliance
12 in (30 cm)
K
Clearance to a mechanical air supply inlet
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) for mechanical draft systems (Category
I 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
12 in (30 cm) - open on 3 sides*
