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18-IN. MINIMUM
TO BURNERS
Fig. 16--1nstNtation
in a Garage
A93044
F[ RNA(E
CORROSION
HAZARD
Air _br con_bustion
must
not be contaminated
by halogen
compounds,
which
include
fluoride,
chloride,
bromide,
and
iodide.
These
elements
could
corrode
heat exchangers
and
shorten
fhmace
life. Air contaminants
are found
in aerosol
sprays,
detergents,
bleaches,
cleaning
solvents,
salts,
air
fresheners,
and other household
products.
The
following
types
of fl_mace
installations
may require
OUT°
DOOR
AIR fbr combustion
due to chemical
exposures:
°
Commercial
buildings
°
Buildings
with
indoor
pools
°
LaundQ-
rooms
*
Hobby
or craft rooms,
and
*
Chemical
storage
areas
If air is exposed
to the fbllowing
substances,
it should
not be used
for combustion
air, and outdoor
air may be required
_br eombus°
tion:
Permanent
wave solutions
Chlorinated
waxes
and cleaners
Chlorine
based
swimming
pool
chemicals
Water
sokening
chemicals
Deqcing
salts or chemicals
Carbon
tetrachloride
Halogen
type refrigerants
Cleaning
solvents
(such as perchloroethylene)
Printing
inks, paint removers,
varnishes,
etc.
Hydrochloric
acid
Cements
and glues
Antistatic
_hbric softeners
_br clothes
dQ'ers
Masonry
acid washing
materials
All fuel=burning
equipment
must
be
supplied
with
air fbr Net
combustion.
Sufficient
air must
be provided
to avoid
negative
pressure
in the equipment
room or space. A positive
seal must
be
made
between
the
Nmace
cabinet
and
the
returnoair
duct
to
prevent
pulling
air fi'om the burner
area and from
&aft safeguard
opening.
CARBON
MONOXIDE
POISONING
HAZARD
The
operation
of
exhaust
fans,
kitchen
ventilation
_ms,
clothes
&yers,
attic exhaust
fans or fireplaces
could
create
a
NEGATIVE
PRESSURE
(ONDITION
at
the
furnace.
Make-up
air MUST
be provided
for the ventilation
devices,
in
addition
to that required
by the fl/rnace.
Refer
to the (arbon
Monoxide
Poisoning
Hazard
warning
in the venting
section
of these
instructions
to determine
if an adequate
amount
of
make=up
air is available.
The requirements
for combustion
and ventilation
air depend
upon
whether
or not the fl/mace
is located
in a space having
a volmne
of at least 50 cubic
feet per 1,000 Bmh
input
rating
ibr all gas
appliances
installed
in the space.
Spaces
having
less d-_an 50 cubic
feet per 1,000 Bmh
require
the O[ TDOOR
(OMB[
STION
AIR METHOD.
Spaces
having
at least 50 cubic feet per 1,000 Btuh may use the
INDOOR
( OMBUSTION
AIR,
STANDARD
or KNOWN-
AIR INFILTRATION
METHOD.
Outdoor
(ombustion
Air Method
1. Provide
the space
with
sufficient
air %r proper
congbustion,
ventilation,
and dilution
of flue gases
using
pem_anent
hori-
zontal
or vertical
duct(s)
or opening(s)
directly
comnmnicat-
ing with the outdoors
or spaces
that freely
communicate
with
the outdoors
2_
Fig. 17 illustrates
how to provide
TWO OUTDOOR
OPEN-
INGS, one inlet and one outlet combustion
and ventilation
air
openings
to the outdoors.
a. One opening
MUST
commence
within
12" (300 mm) of
the
ceiling
and
the
second
opening
MUST
commence
within
12" (300 mm) of the floor.
b. Size openings
and ducts per Fig. 17 and Table
1.
c. TWO
HORIZONTAL
DUCTS
require
1 square
inch of
free area per 2,000
Btuh
(1,100
mm2ikW)
of combined
input
fi_r all gas appliances
in the space
per Fig.
17 and
Table
1.
d_
TWO OPEND._GS OR VERTI(AL
DUCTS require
1
square inch of flee area per 4,000 Btuh (550 ram2 kW) _br
combined input of all gas appliances in the space per Fig.
17 and Table 1
3. ONE OUTDOOR OPENING requires:
a. 1 square inch of flee area per 3,000 Btnh (734
n'lnl2ikW)
for combined input of all gas appliances in the space per
Table 1 and
b. Not tess than the sum of the areas of all vent connectors
in
the space
The opening
shall commence
within
12" (300 mm) of the
ceiling.
Appliances
in the space
shall have clearances
of at
least 1" (25 ram) from the sides and back and 6" (150 mm)
fiom
the
front.
The opening
shall
directly
communicate
with the outdoors
or shall communicate
through
a vertical
or horizontal
duct to the outdoors
or spaces
(crawl or attic)
that fl-eely communicate
with the outdoors.
Indoor
Combustion
Air_)
NFPA
& AGA
Standard
and Known-Air-InfiRration
Rate Methods
Indoor
air is permitted
%r combustion,
ventilation,
and dilution,
if the Slandard
or Known-Air-InfiRration
Method
is used
15
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