Navien NPE-180A2 Installation Manual page 49

Non-Direct Venting (Single Pipe)
If, at any time, the installation location could
experience negative pressure, there is a possibility
of back drafting cold air through the water heater's
heat exchanger. This situation could lead to the
freezing of the heat exchanger and malfunction of
the water heater.
However, building codes in most jurisdictions
disallow negative pressures in residences. In a
home with a well-balanced air supply, the heat
exchanger should not be in danger of freezing.
Because the cause of back drafting is not considered
a manufacturing problem, any freezing damage
which occurs from back drafting will not be covered
by the Navien warranty. If there is any question
about the possibility of back drafting in the
installation location, use a direct venting system for
the water heater.
When installed in a manufactured home, all
combustion air must be supplied from the outdoors
as described on page 40.
WARNING
Carbon Monoxide Hazard
NEVER install this water heater in a recreational
vehicle, trailer, boat or other moving vehicle to
prevent serious injury or death.
When using non-direct venting, maintain non-direct
vent clearances shown on page 50 as required by
CSA/ANSI Z21.10.3 and the National Fuel Gas
Code, ANSI Z223.1/NFPA 54, and CAN/CSA
B149.1 Natural Gas And Propane Installation
Code.
To use non-direct venting for the water heater:
1. Insert the termination end cap into the intake
air duct.
Do NOT glue the end cap to allow for
Note
easy removal and cleaning of the cap.
Vent termination
cap 2 in.
Coupling 2 in.
Pipe 2 in.
2. The equipment room MUST be provided with
properly sized openings to assure adequate
combustion air.
3. Combustion air requirements are based on the
latest edition of the National Fuel Gas Code,
NFPA 54 / ANSI Z223.1; in Canada refer to the
latest edition of CGA Standard CAN/CSA B149.1.
All local codes supersede these clearance
requirements when applicable.
Outdoor
make up air is
Maximum provided,
Input a minimum
(BTU/H) free area of
1 in
4,000 BTU/H
30 in
NPE-
10 in. (W) x
120,000
150S2
3 in. (H) or 6 in.
round
NPE-
40 in
180A2
10 in. (W) x
150,000
NPE-
4 in. (H) or 7 in.
180S2
round
NPE-
45 in
210A2 10 in. (W) x
180,000
NPE-
5 in. (H) or 8 in
210S2
round
NPE-
50 in
240A2
10 in. (W) x
199,900
NPE-
5 in. (H) or 8 in.
240S2 round
Indoor make
up air is
provided,
a minimum
free area of
. per 1 in . per
2 2
1,000 BTU/H
.
2
120 in .
2
11 in. (W) x
11 in. (H)
.
2
150 in .
2
12 / in. (W) x
1
4
12 / in. (H)
1
4
.
2
180 in .
2
13 / in. (W) x
1
4
13 / in. (H)
1
4
.
2
199 in .
2
14 / in. (W) x
1
4
14 / in. (H)
1
4
Installing the Water Heater 49