Instructions / Assembly

8
Installing the water heater
Combustion and Ventilation Air
Proper operation of the water heater
requires air for combustion and ventilation.
Provisions for combustion and ventilation
air must comply with referenced codes and
standards.
DO NOT block or obstruct any of the
combustion air inlet openings located
around the perimeter of the water heater.
A minimum of 1 in. (2.54 cm) is required
between these combustion air inlet openings
and any obstruction.
NOTICE: If the water heater is installed
in an unconfined space within a building
of conventional frame, masonry or metal
construction, infiltration air is normally
adequate for proper combustion and
ventilation. If the water heater is installed in
a confined space, provisions for combustion
and ventilation air must be made.
DO NOT obstruct or block the Flammable
Vapor Sensor.
A confined space is one having a volume of
less than 50 cubic feet per 1,000 Btu/H (1.42
cubic meters per .29 kw) of the aggregate
input of all appliances within that space.
The air must be supplied through two
permanent openings of equal area. One is to
be located within 12 in. (30.5 cm) above the
floor and the other is to be located within 12
in. (30.5 cm) from the ceiling.
The minimum net free area of each opening
must not be less than one square inch (6.45
square cm) per 1,000 Btu/h of the total input
rating of all the appliances in the enclosure
[but not less than 100 square inches (6.45
square cm)], if each opening communicates
with other unconfined areas inside the
building.
Buildings of unusually tight construction
shall have the combustion and ventilation
air supplied from outdoors, or a freely
ventilated attic or crawl space.
If air is supplied from outdoors, directly or
through vertical ducts, there must be two
openings located as specified above and
each must have a minimum net free area of
not less than one square inch (6.45 square
cm) per 4,000 Btu/h (1.17 kw) of the total
input rating of all the appliances in the
enclosure.
If horizontal ducts are used to communicate
with the outdoors, each opening must have
a minimum net free area of not less than
one square inch (6.45 square cm) per 2,000
Btu/h (.58 kw) of the total input rating of
all the appliances in the enclosure. If ducts
are used, the minimum dimensions of
rectangular air ducts shall not be less than 3
in. (7.6 cm)
NOTICE: If the duct openings which
supply combustion and ventilation air are
to be covered with a protective screen or
grill, the net free area (openings in the
material) of the covering material must be
used in determining the size of the openings.
Protective screening for the openings MUST
NOT be smaller than 1/4 in. (.64 cm) mesh
to prevent clogging by lint or other debris.
Corrosive Atmospheres
The air in beauty shops, dry cleaning
establishments, photo processing
labs, and storage areas for liquid and
powdered bleaches or swimming pool
chemicals often contain such halogenated
hydrocarbons.
An air supply containing halogenated
hydrocarbons may be safe to breathe,
but when it passes through a gas flame
corrosive elements are released that
will shorten the life of any gas burning
appliance.
Propellants from common spray cans
or gas leaks from A/C and refrigeration
equipment are highly corrosive after
passing through a flame.
The water heater warranty is voided when
failure of the heater is due to operation in
a corrosive atmosphere.
NOTICE: The water heater
should not be installed near
an air supply containing
halogenated hydrocarbons.