COMBUSTION AIR SUPPLY & VENTILATION
WARNING
Carbon Monoxide Warning
Follow all the local and state codes or, in the absence of local and state codes, the “National Fuel Gas Code”, ANSI Z223.1 (NFPA 54)- current edition to properly install vent system.
Failure to do so can result in death, explosion, or carbon monoxide poisoning.
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
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
Unconfined Space
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.
TABLE 3
| Minimum Square | Typical Room | |
BTUH Input | Feet with | ||
with 8’ Ceiling | |||
| 8’ Ceiling | ||
|
| ||
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 |
TABLE 3
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.
Confined Space
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 12.
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.
12” MAXIMUM
|
|
| CLOSET |
|
|
| |
PERMANENT |
| OR | |
| OTHER | ||
OPENINGS TO |
| CONFINED | |
THE OUTSIDE OR |
| SPACE | |
ADDITIONAL |
|
| |
ROOMS WITHIN |
|
| |
THE BUILDING |
|
| |
12” MAXIMUM 
FIGURE 12.
All Air from Inside the Building
When additional air is to be provided to the confined area from additional room(s) within the building, the total volume of the room(s) must be of sufficient size to properly provide the necessary amount of fresh air to the water heater and other
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