AIR FOR COMBUSTION
AND VENTILATION
Continued
DETERMINING FRESH-AIR FLOW FOR FIREPLACE LOCATION
Determining if You Have a Confined or Unconfined Space
Use this work sheet to determine if you have a confined or unconfined space.
Space: Includes the room in which you will install fireplace plus any adjoining rooms with doorless pas- sageways or ventilation grills between the rooms.
1.Determine the volume of the space (length x width x height).
Length x Width x Height =__________cu. ft. (volume of space)
Example: Space size 16 ft. (length) x 14 ft. (width) x 8 ft. (ceiling height) = 1792 cu. ft. (vol- ume of space)
If additional ventilation to adjoining room is sup- plied 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: 1792 cu. ft. (volume of space) x 20 = 35,840 (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:
Gas water heater |
| 30,000 | Btu/Hr |
+ | 10,000 | Btu/Hr | |
Total | = | 40,000 | Btu/Hr |
4.Compare the maximum Btu/Hr the space can sup- port with the actual amount of Btu/Hr used.
________ | Btu/Hr (maximum the space can support) |
________ | Btu/Hr (actual amount of Btu/Hr used) |
Example: 35,840 Btu/Hr (maximum the space can support)
40,000 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 uncon- fined 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 unconfined 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/NFPA 54 Section
5.3or applicable local codes.
VENTILATION AIR
Ventilation Air From Inside Building
This fresh air would come from an adjoining uncon- fined space. When ventilating to an adjoining un- confined 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 4, page 9). You can also remove door into adjoining room (see option 3, Fig- ure 4, page 9). Follow the National Fuel Gas Code, ANSI Z223.1/NFPA 54, Section 5.3, Air for Com- bustion and Ventilation for required size of ventila- tion grills or ducts.
Ventilation Air From Outdoors
Provide extra fresh air by using ventilation grills or ducts. You must provide two permanent open- ings: 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.
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