AIR FOR COMBUSTION
AND VENTILATION
Continued
The space in the above 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 additional fresh air. Your options are as follows:
A.Rework work sheet, adding the space of an adjoining room. If the extra space provides an unconfined 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 Ven- tilation Air from Outdoors.
C.Install a lower Btu/Hr gas log heater, if lower Btu/Hr size makes room unconfined.
If the actual Btu/Hr used is less than the maxi- mum Btu/Hr the space can support, the space is an unconfined space. You will need no additional fresh air ventilation.
WARNING: If the area in which the firebox and gas log heater may be operated 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, ANS Z223.1/NFPA54, Section 5.3 or applicable local codes.
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 perma- nent openings: one within 12" of the ceiling and one within 12" of the floor on the wall connecting the two spaces (see option 1, Figure 3). You can also remove door into adjoining room (see op- tion 2, Figure 3). Follow the National Fuel Gas Code ANS Z223.1/NFPA 54, Section 5.3, Air for Combustion and Ventilation for required size of ventilation grills or ducts.
WARNING: Rework work- sheet, adding the space of the adjoining unconfined space. The combined spaces must have enough fresh air to supply all appliances in both spaces.
Ventilation |
| |
Grills |
| |
Into Adjoining | Or | |
Room, | ||
Remove | ||
Option 1 | ||
Door into | ||
| ||
| Adjoining | |
| Room, | |
| Option | |
| 2 |
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 ANS 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 | |
|
|
Figure 4 - Ventilation Air from Outdoors
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