(100) square inches (645.16 cm²). The first opening
should be situated within six (6) inches (15.2 cm) of
the top and the second opening within six (6) inches
(15.2 cm) of the bottom of the confined space.
2) All Air From Outdoors:
The confined space shall be provided with two (2
permanent openings, the first opening within six (6)
inches (15.2 cm) of the top and the second within
six (6) inches (15.2 cm) from the bottom of the
confined space. The openings shall communicate
directly, or by ducts, with the outdoors or spaces
(crawl or attic) that freely communicates with the
outdoors.
A) When communicating directly with the outdoors,
each opening shall have a minimum free area of
one (1) square inch per 4,000 Btuh (5.5 cm²/kW) of
the total input rating of all gas appliances in the
confined space (see Figure 4).
Confined Space
Permanent
Opening
--------------
1 square inch /
1,000 Btuh
(min.: 100 sq. in)
Outlet air to attic
1 sq. in / 4,000 Btuh
Attic air inlet
Install above
insulation
Confined Space
Inlet air from the
crawl space
1 sq. in / 4,000 Btuh
Open foundation vent
Install above
insulation
Attic air inlet
Outlet air to attic
1 sq. in / 4,000 Btuh
Confined Space
Inlet air duct
1 sq. in / 4,000 Btuh
12'' max.
Inlet
Outlet
Outdoor air duct
1 sq. in. / 2,000 Btuh
1 sq. in. / 2,000 Btuh
Confined Space
Alternate
air inlet
Entrée d'air
Alternative
1 po
2
/ 2 000 BTUH
1 po
2
/ 2 000 BTUH
Conduit d'air extérieur
Sortie
Entrée
12'' max.
Conduit d'entrée d'air
1 po
2
/ 4 000 BTUH
Évent de fondation
1 po
2
/ 4 000 BTUH
Entrée d'air du
sous-sol
Espace Restreint
Installez au-dessus
de l'isolation
Entrée d'air
du grenier
Sortie d'air
au grenier
1 po
2
/ 4 000 BTUH
Ouverture
Permanente
--------------
1 pouce carré /
1 000 BTUH
(min. : 100 po
2
)
Espace Restreint
Entrée d'air
du grenier
Installez au-dessus
de l'isolation
Espace Restreint
Sortie d'air
au grenier
1 po
2
/ 4 000 BTUH
Espace Restreint
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Figure 4
B) When communicating with the outdoors through
vertical ducts, each opening shall have a minimum
free area of one (1) square inch per 4,000 Btuh
(5.5 cm²/kW) of the total input rating of all gas
appliances in the confined space (see Figure 5).
Confined Space
Permanent
Opening
--------------
1 square inch /
1,000 Btuh
(min.: 100 sq. in)
Outlet air to attic
1 sq. in / 4,000 Btuh
Attic air inlet
Install above
insulation
Confined Space
Inlet air from the
crawl space
1 sq. in / 4,000 Btuh
Open foundation vent
Install above
insulation
Attic air inlet
Outlet air to attic
1 sq. in / 4,000 Btuh
Confined Space
Inlet air duct
1 sq. in / 4,000 Btuh
12'' max.
Inlet
Outlet
Outdoor air duct
1 sq. in. / 2,000 Btuh
1 sq. in. / 2,000 Btuh
Confined Space
Alternate
air inlet
Entrée d'air
Alternative
1 po
2
/ 2 000 BTUH
1 po
2
/ 2 000 BTUH
Conduit d'air extérieur
Sortie
Entrée
12'' max.
Conduit d'entrée d'air
1 po
2
/ 4 000 BTUH
Évent de fondation
1 po
2
/ 4 000 BTUH
Entrée d'air du
sous-sol
Espace Restreint
Installez au-dessus
de l'isolation
Entrée d'air
du grenier
Sortie d'air
au grenier
1 po
2
/ 4 000 BTUH
Ouverture
Permanente
--------------
1 pouce carré /
1 000 BTUH
(min. : 100 po
2
)
Espace Restreint
Entrée d'air
du grenier
Installez au-dessus
de l'isolation
Espace Restreint
Sortie d'air
au grenier
1 po
2
/ 4 000 BTUH
Espace Restreint
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Figure 5
C) When communicating with the outdoors through
horizontal ducts, each opening shall have a minimum
free area of one (1) square inch per 2,000 Btuh
(11.0 cm²/kW) of the total input rating of all gas
appliances in the confined space (see Figure 6).
Confined Space
Permanent
Opening
--------------
1 square inch /
1,000 Btuh
(min.: 100 sq. in)
Outlet air to attic
1 sq. in / 4,000 Btuh
Attic air inlet
Install above
insulation
Confined Space
Inlet air from the
crawl space
1 sq. in / 4,000 Btuh
Open foundation vent
Install above
insulation
Attic air inlet
Outlet air to attic
1 sq. in / 4,000 Btuh
Confined Space
Inlet air duct
1 sq. in / 4,000 Btuh
12'' max.
Inlet
Outlet
Outdoor air duct
1 sq. in. / 2,000 Btuh
1 sq. in. / 2,000 Btuh
Confined Space
Alternate
air inlet
Entrée d'air
Alternative
1 po
2
/ 2 000 BTUH
1 po
2
/ 2 000 BTUH
Conduit d'air extérieur
Sortie
Entrée
12'' max.
Conduit d'entrée d'air
1 po
2
/ 4 000 BTUH
Évent de fondation
1 po
2
/ 4 000 BTUH
Entrée d'air du
sous-sol
Espace Restreint
Installez au-dessus
de l'isolation
Entrée d'air
du grenier
Sortie d'air
au grenier
1 po
2
/ 4 000 BTUH
Ouverture
Permanente
--------------
1 pouce carré /
1 000 BTUH
(min. : 100 po
2
)
Espace Restreint
Entrée d'air
du grenier
Installez au-dessus
de l'isolation
Espace Restreint
Sortie d'air
au grenier
1 po
2
/ 4 000 BTUH
Espace Restreint
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Gas vent to
outdoors
Évacuation de gaz
vers l'extérieur
Figure 6
When ducts are used, they shall be of the same
cross-sectional area as the free area of the openings
to which they connect. The minimum short side
dimension of rectangular air ducts shall not be less
than three (3) inches (7.62 cm).
Louvers and Grilles
In calculating free area for ventilation and combustion
air supply openings, consideration must be given
to the blocking effect of louvers, grilles, or screens
protecting the openings. Screens must not be smaller
than 1/4 inch (6.4 mm) mesh. If the free area through
a particular design of louver or grille is known, it
should be used in calculating the size of opening
required to provide the free area specified. If the
design and free area is unknown, it may be assumed
that wood louvers and grilles will allow 20-25% free
area and metal louvers and grilles will allow 60-75%
free area. Louvers and grilles must be installed in the
open position or interconnected with the water heater
so that they are opened automatically during water
heater operation.
Corrosive Atmospheres
If this water heater will be installed in a beauty shop,
barber shop, photo processing lab, dry cleaning
establishment, a building with an indoor pool, or
near a chemical storage area, it is imperative that
the combustion and ventilation air be drawn from
outside these areas. These particular environments
contain products such as aerosol sprays, detergents,
bleaches, cleaning solvents, refrigerants, and other
volatile compounds that, in addition to being highly
flammable, become highly corrosive acid compounds
when burned. Exposure to such compounds can be
hazardous and lead to premature product failure.
Should the water heater fail due to exposure to
such a corrosive atmosphere, the warranty is void.
6
INSTALLATION INSTRUCTIONS
