Navien NPE-180A2 Installation Manual page 47

3.6.3 Selecting a Vent Type
Navien NPE Series water heaters are Category IV appliances and are prepared at the factory to be direct vent
(sealed combustion) appliances that draw all of their required combustion air directly from the outdoors. Navien
recommends direct air vent installations whenever possible to avoid back drafting cold air through the water
heater. 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 water heater.
Direct Venting
The water heater uses 2 in. or 3 in. diameter exhaust and 2 in. or 3 in. diameter intake air 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
water heater collar to the vent termination.
Intake materials can be made of ABS, PVC, CPVC, PP, galvanized 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 CSA/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:
Ref Description
Clearance above grade, veranda,
A
porch, deck, or balcony
Clearance to window or door
B
that may be opened
Clearance to permanently closed
C
window
Inside
corner detail
Legend:
= Vent Terminal
= Air Supply Inlet
= Area where
terminal is not permitted
Canadian installations
1
12 in. (30 cm)
36 in. (91 cm) for appliances
>100,000 Btuh (30 kW)
12 in. (30 cm)*
REGULATOR VENT OUTLET
In the event no regulator
is present, H and I can be
disregarded.
US installations
2
12 in. (30 cm)
12 in. (30 cm) for appliances >
50,000 Btuh (15 kW)
12 in. (30 cm)*
Installing the Water Heater 47