A.O. Smith GAHH 40 100 ユーザーズマニュアル

7

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 outdoor air to function properly. In 

this situation, outside air openings should be 

sized the same as for a confined space. 

•  Modern home construction usually requires 

supplying outside air into the water heater 

area.

•  Room exhaust fans may effect air 

requirements.

Confi ned Space: For the correct and proper 

operation of this water heater, ample air must be 

supplied for the combustion, ventilation, and dilu-

tion of fl ue gases. Small enclosures and confi ned 

areas must have two permanent openings so that 

suffi cient 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.

The size of each opening (free area) is deter-

mined 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 fl ammable or corrosive at-

mosphere. Any failure due to fl ammable or corro-

sive elements in the atmosphere is excluded from 

warranty coverage.

The following types of installation (not limited to 

the following) will require outdoor air for combus-

tion due to chemical exposure and may reduce 

but not eliminate the presence of corrosive chemi-

cals 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

• water 

softeners

Combustion air must be free of acid-forming 

chemicals such as sulfur, fl uorine, and chlorine. 

These elements are found in aerosol sprays, de-

tergents, bleaches, cleaning solvents, air freshen-

ers, paint, and varnish removers, refrigerants, and 

many other commercial and household products. 

When burned, vapors from these products form 

highly corrosive acid compounds. These prod-

ucts should not be stored or used near the water 

heater, air inlet, or air intake path.

Combustion and ventilation air requirements are 

determined by the location of the water heater. 

The water heater may be located in either an 

open (unconfi ned) area or in a confi ned area or 

small enclosure such as a closet or small room. 

Confi ned spaces are areas with less than 50 cubic 

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

gas-using appliances.

Unconfi ned Space: A water heater in an uncon-

fi ned 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 mini-

mum square footage (area) required for various 

BTUH inputs.