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USSC 7
VENTILATION INSTALLATION continued...
Clearance above grade, veranda, porch,
deck, or balcony
Clearnace to window or door that may be
opened
Clearance to permanently closed window
Vertical clearance to ventilated soffit lo-
cated above the terminal within a horizon-
tal distance of 2 feet (61 cm) from the cen-
ter line of the terminal
Clearnace to unventilated soffit
Clearance to outside corner
Clearnace to inside corner
Clearnace to each side of center line ex-
tended above meter/regulator assembly
Clearance to service regulator vent outlet
Clearance to nonmechanical air supply in-
let to building or the combustion air inlet to
any other appliance
Clearance to a mechanical air supply inlet
Clearnace above paved sidewalk or paved
driveway located on publis property
Clearance under veranda, porch, deck, or
balcony
A =
B =
C =
D =
E =
F =
G =
H =
I =
J =
K =
L =
M =
12 inches (30 cm)
6 inches (15 cm) for appliance < 10,000 BTU/hr
(3 kW), 12 inches (30 cm) for appliance > 10,000
BTU/hr (3 kW) and <100,000 BTU/hr (30 kW),
36 inches (91 cm) for appliances > 100,000 BTU/
hr (30 kW)
*
*
*
*
*
3 feet (91 cm) within a hieght 15 feet (4.5 m)
above the meter/regulator assembly
3 feet (91 cm)
6 inches (15 cm) for appliance < 10,000 BTU/hr
(3kW), 12 inches (30 cm) for appliance > 10,000
BTU/hr (3kW) and < 100,000 BTU/hr (30 kW),
36 inches (91 cm) for appliance > 100,000 BTU/
hr (30 kW)
6 feet (1.83 m)
7 feet (2.13 m) †
12 inches (30 cm) ‡
12 inches (30 cm)
6 inches (15 cm) for appliance < 10,000 BTU/hr
(3 kW), 9 inches (23 cm) for appliance > 10,000
BTU/hr (3 kW) and < 50,000 BTU/hr (15 kW), 12
inches (30 cm) for appliances > 50,000 BTU/hr
(15 kW)
*
*
*
*
*
*
*
6 inches (15 cm) for appliance < 10,000 BTU/hr
(3kW), 9 inches (23 cm) for appliance > 10,000
BTU/hr (3kW) and < 50,000 BTU/hr (15 kW), 12
inches (30 cm) for appliance > 50,000 BTU/hr
(15 kW)
3 feet (91 cm) above if within 10 feet (3 m)
horizontally
*
*
Canadian Installation
1
US Installation
2
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 paved sidewalk or paved driveway that is located between two single family dwellings and serve both dwellings.
‡ Permitted only if verdana, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor.
* For clearnaces not specified in ANSI Z223.1/NFPA 54 or CSA B149.1, one of the following shall be indicated.
(a) A minimum clearances valve determined by testing in accordance with section 2.19.6, or ;
(b) A reference to the following footnote:
“ Clearance in accordance with local installation codes and the requirements of the gas supplier.”