Navien NFB-175H, Installation Manual, Page: 60 / 135

60 Venting for Combustion Air
Ref Description
Canadian Direct
Vent Installations
1
US Direct Vent
Installations
2
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
* *
E Clearance to unventilated soffit * *
F Clearance to outside corner * *
G Clearance to inside corner * *
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
*
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
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)
†
*
M Clearance under veranda, porch deck, or balcony 12 in (30 cm)
‡
*
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.
* Clearance in accordance with local installation codes and the requirements of the gas supplier.