American Water Heater 317994-002 Manual De Usuario

11

TABLE 3

30,000

188

9 x 21

45,000

281

14 x 20

60,000

375

15 x 25

75,000

469

15 x 31

90,000

563

20 x 28

105,000

657

20 x 33

120,000

750

25 x 30

135,000

844

28 x 30

IMPORTANT:
• 

The area must be open and be able to provide the 

proper air requirements to the water heater. Areas that 

are being used for storage or contain large objects 

may not be suitable for water heater installation. 

• 

Water heaters installed in open spaces in buildings 

with unusually tight construction may still require out-

door air to function properly. In this situation, outside 

air openings should be sized the same as for a con-

fined space. 

• 

Modern home construction usually requires supplying 

outside air into the water heater area. 

For the correct and proper operation of this water heater, 

ample air must be supplied for the combustion, ventilation, 

and dilution of flue gases. Small enclosures and confined 

areas must have two permanent openings so that sufficient 

fresh air can be drawn from outside of the enclosure. One 

opening shall be within 12 inches of the top and one within 

12 inches of the bottom of the enclosure as shown in 

Figure 4.
The size of each opening (free area) is determined by the 

total BTUH input of all gas utilization equipment (i.e., water 

heaters, furnaces, clothes dryers, etc.) and the method by 

which the air is provided. The BTUH input can be found 

on the water heater rating plate. Additional air can be 

provided by two methods:

1.   All air from inside the building.
2.   All air from outdoors.

IMPORTANT:  Air for combustion and ventilation must not 

come from a corrosive atmosphere. Any failure due to 

corrosive elements in the atmosphere is excluded from 

warranty coverage.
The following types of installation (not limited to the 

following) will require outdoor air for combustion due to 

chemical exposure and may reduce but not eliminate the 

presence of corrosive chemicals in the air:
• beauty 

shops

• 

photo processing labs

• 

buildings with indoor pools 

• 

water heaters installed in laundry, hobby, or craft 

rooms

• 

water heaters installed near chemical storage areas

Combustion air must be free of acid-forming chemicals such 

as sulfur, fluorine, and chlorine. These elements are found 

in aerosol sprays, detergents, bleaches, cleaning solvents, 

air fresheners, paint, and varnish removers, refrigerants, 

and many other commercial and household products. When 

burned, vapors from these products form highly corrosive acid 

compounds. These products should not be stored or used 

near the water heater or air inlet.
Combustion and ventilation air requirements are determined 

by the location of the water heater. The water heater may 

be located in either an open (unconfined) area or in a 

confined area or small enclosure such as a closet or small 

room. Confined spaces are areas with less than 50 cubic 

feet for each 1,000 BTUH of the total input for all gas-using 

appliances.

A water heater in an unconfined space uses indoor air for 

combustion and requires at least 50 cubic feet for each 

1,000 BTUH of the total input for all gas appliances. The 

table below shows a few examples of the minimum square 

footage (area) required for various BTUH inputs.