Navien NFC-250/175H, Руководство по установке, Страница: 70 / 151

70 Venting for Combustion Air
2. Provide two openings to allow for circulation
of combustion air as specified by ANSI Z223.1/
NFPA 54 or CAN/CGA B-149.1:
Maximum
Input
(BTU/H)
Outdoor
make up air
is provided,
a minimum
free area of
1 in
2
, per
4,000 BTU/H
Indoor make
up air is
provided, a
minimum
free area of
1 in
2
, per
1,000 BTU/H
NFC-
250/200H
210,000
53 in
2
10 in (W) x
6 in (H) or
9 in round
210 in 2
14 1 /
2
in (W) x
14 1 /
2
in (H)
NFC-
250/175H
210,000
53 in 2
10 in (W) x
6 in (H) or
9 in round
210 in
2
14
1
/
2
in (W) x
14
1
/
2
in (H)
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 boiler’s heat
exchanger. This situation could lead to the freezing
of the heat exchanger and malfunction of the boiler.
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 boiler.
When using non-direct venting, maintain non-direct
vent clearances shown on page 71 as required by
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 boiler:
1. Insert the termination end cap into the intake
air duct. Do not glue the end cap, to allow for
easy removal and cleaning of the cap.
Vent Termination
Cap 2"
Coupling 2"
Vent Pipe 2"