AIR FOR COMBUSTION
AND VENTILATION
Continued
Example: Space size 20 ft. (length) x 16 ft. (width) x 8 ft. (ceiling height) = 2,560 cu. ft. (volume of space)
If additional ventilation to adjoining room is supplied with grills or openings, add the volume of these rooms to the total volume of the space.
2.Multiply the space volume by 20 to determine the maximum Btu/Hr the space can support.
__________ (volume of space) x 20 = (Maxi- mum Btu/Hr the space can support)
Example: 2,560 cu. ft. (volume of space) x 20 = 63,360 (maximum Btu/Hr the space can support)
3.Add the Btu/Hr of all fuel burning appliances in the space.
__________ Btu/Hr | |
Gas water heater* | __________ Btu/Hr |
Gas furnace | __________ Btu/Hr |
Vented gas heater | __________ Btu/Hr |
Gas fireplace logs | __________ Btu/Hr |
Other gas appliances* | +__________ Btu/Hr |
Total | =__________ Btu/Hr |
*Do not include
Example: | 40,000 | |
Gas water heater | ||
__________ Btu/Hr | ||
33,000 | ||
+__________ Btu/Hr | ||
Total | 73,000 | |
=__________ Btu/Hr |
If the actual Btu/Hr used is less than the maximum Btu/Hr the space can support, the space is an uncon- fined 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.
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.
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: 63,360 Btu/Hr (maximum the space can support)
73,000 Btu/Hr (actual amount of Btu/Hr used)
Ventilation |
| |
Grills |
| |
Into | Or | |
Adjoining | ||
Remove | ||
Room, | ||
Door into | ||
Option 1 | ||
Adjoining | ||
| ||
| Room, | |
| Option | |
| 3 |
12"
Ventilation Grills
Into Adjoining Room,
Option 2
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 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.
12"
Figure 3 - Ventilation Air from Inside
Building
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