AIR FOR COMBUSTION
AND VENTILATION
Continued
Example: |
| 40,000 |
|
Gas water heater |
| Btu/Hr | |
+ | 33,000 | Btu/Hr | |
Total | = | 73,000 | Btu/Hr |
4.Compare the maximum Btu/Hr the space can support with the actual amount of Btu/Hr used.
__________ Btu/Hr (maximum the space can support)
__________ Btu/Hr (actual amount of Btu/Hr used) Example: 51,200 Btu/Hr (maximum the space
can support)
VENTILATION AIR
Ventilation Air From Inside Building
This fresh air would come from an adjoining un- confined space. When ventilating to an adjoining unconfined space, you must provide two permanent openings: one within 12" of the ceiling and one within 12" of the floor on the wall connecting the two spaces (see options 1 and 2, Figure 3). You can also remove door into adjoining room (see option 3, Figure 3). Follow the National Fuel Gas Code, ANSI Z223.1/NFPA 54, Section 5.3, Air for Combustion and Ventilation for required size of ventilation grills or ducts.
73,000 Btu/Hr (actual amount of Btu/Hr used)
The space in the example is a confined space because the actual Btu/Hr used is more than the maximum Btu/Hr the space can support. You must provide ad- ditional fresh air. Your options are as follows:
A. Rework worksheet, adding the space of an adjoin- |
ing room. If the extra space provides an unconfined |
Ventilation |
| |
Grills |
| |
Into Adjoining | Or | |
Room, | ||
Remove | ||
Option 1 | ||
Door into | ||
| ||
| Adjoining | |
| Room, | |
| Option | |
| 3 |
12"
Ventilation Grills
Into Adjoining Room,
Option 2
space, remove door to adjoining room or add |
ventilation grills between rooms. See Ventilation |
Air From Inside Building. |
B. Vent room directly to the outdoors. See Ventila- |
tion Air From Outdoors. |
C. Install a lower Btu/Hr fireplace, if lower Btu/Hr |
size makes room unconfined. |
If the actual Btu/Hr used is less than the maximum Btu/Hr the space can support, the space is an un- confined space. You will need no additional fresh air ventilation.
WARNING: If the area in which the heater may be oper- ated is smaller than that defined as an unconfined space or if the building is of unusually tight construction, provide adequate combustion and ventilation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1/NFPA54 Section 5.3 or applicable local codes.
12"
Figure 3 - Ventilation Air from Inside
Building
Ventilation Air From Outdoors
Provide extra fresh air by using ventilation grills or ducts. You must provide two permanent openings: one within 12" of the ceiling and one within 12" of the floor. Connect these items directly to the outdoors or spaces open to the outdoors. These spaces include attics and crawl spaces. Follow the National Fuel Gas Code, ANSI Z223.1/NFPA 54, Section 5.3, Air for Combustion and Ventilation for required size of ventilation grills or ducts.
IMPORTANT: Do not provide openings for inlet or outlet air into attic if attic has a thermostat- controlled power vent. Heated air entering the attic will activate the power vent.
| Outlet | Ventilated |
| Attic | |
| Air | |
|
| |
Outlet |
|
|
Air |
| To Attic |
|
| |
|
| To |
|
| Crawl |
Inlet |
| Space |
|
| |
Air |
|
|
| Inlet Air | Ventilated |
| Crawl Space | |
|
|