G= Clearance to inside corner of combustible surface
J= Clearance to nonmechanical
air supply inlet to building or
the combustion air inlet to
any other appliance
for appliances >100,000 Btuh (30kW)
K= Clearance to a mechanical
air supply inlet
L= Clearance above paved sidewalk 7 ft (2.13 m) †
or paved driveway located on
public property
M= Clearance under veranda,
porch deck or balcony
0"
3"
6 in (15cm) for appliances ≤10,000
Btuh (3kW), 12 in (30 cm) for
appliances >10,000 Btuh (3kW) and
≤100,000 Btuh (30kW), 36 in (91 cm)
6 ft (1.83 m)
12 in (30 cm) ‡
0"
3"
6 in (15cm) for appliances ≤10,000
Btuh (3kW), 9 in (23 cm) for
appliances >10,000 Btuh (3kW0 and
≤50,000 Btuh (15kW), 12 in (30cm)
for appliances >50,000 Btuh (15kW0
3 ft (91 cm) above if within 10ft
(3 m) horizontally
*
*
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
For clearances not specified in ANSI Z223.1 /
*
NFPA 54 or CSA B149.1 one of the following
shall be indicated
a).
A minimum clearance value determined by
testing in accordance with section 2.23.5, or:
b).
A reference to the following footnote:
"Clearance in accordance with local installation
codes and the requirements of the gas supplier."
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