Selecting A Vent Type - Navien NFB-175 Mode D'emploi

5.1 Selecting a Vent Type

All boilers are Category IV appliances and prepared at the factory
to be direct vented (sealed combustion). Navien recommends
direct air vent installations whenever possible to avoid back
drafting cold air through the boiler unit. If you cannot use a direct
vent, ensure that an ample supply of make-up air is available in the
installation location.
Navien also recommends installing a new vent system with this
appliance. If reusing an existing vent system, thoroughly inspect
it for punctures, cracks, or blockages prior to connecting it to the
boiler.
Ref Description
A Clearance above grade, veranda, porch, deck, or balcony
B Clearance to window or door that may be opened
C Clearance to permanently closed window
Vertical clearance to ventilated soffit located above the
D 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
Clearance to each side of center line extended above
H
meter/regulator assembly
I Clearance to service regulator vent outlet
52 Venting the Boiler
Direct Venting
The boiler uses a 2 in or 3 in diameter exhaust and a 2 in or 3 in
diameter air intake ducts. To ensure the draw of air directly from
and exhaust of air directly to the outside of the building, create an
airtight seal from the boiler collar to the vent termination.
Intake materials can be made of ABS, PVC, CPVC, PP, galvanized or
stainless steel, corrugated aluminum or any other such materials. If
you use a corrugated material, ensure that there is not inadvertent
crimping of, or damage to, the intake air pipe.
When using direct venting, maintain the following venting
clearances, as required by ANSI Z21.10.3 and the National Fuel
Gas Code, ANSI Z223.1/NFPA 54, and CAN/CGA B149.1 Natural
Gas and Propane Installation Code:
Canadian Direct Vent Installations
12 in (30 cm)
36 in (91 cm)
*
*
*
*
*
3 ft (91 cm) within a height
15 ft above the meter/regulator
assembly
3 ft (91 cm)
US Direct Vent Installations
1
12 in (30 cm)
12 in (30 cm)
*
*
*
*
*
*
*
2