Air For Combustion and Ventilation
Continued
DETERMINING
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 heater plus any adjoining rooms with doorless passageways 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 22 ft. (length) x 18 ft. (width) x 8 ft. (ceiling height) = 3168 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 deter- mine the maximum Btu/Hr the space can support.
_ _____ (volume of space) x 20 = (Maxi- mum Btu/Hr the space can support)
Example: 3168 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 appli- ances 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 |
| 40,000 | Btu/Hr |
+ | 39,000 | Btu/Hr | |
Total | = | 79,000 | 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: 63,360 Btu/Hr (maximum the
space can support)
79,000 Btu/Hr (actual amount of Btu/Hr used)
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 sup- port. You must provide additional fresh air. Your options are as follows:
A.Rework worksheet, 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, page 8.
B.Vent room directly to the outdoors. See Ventilation Air From Outdoors, page 8.
C.Install a lower Btu/Hr heater, 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:Iftheareainwhich the heater may be operated does not meet the required volume for indoor combustion air, combustion and ventilation air shall be provided by one of the methods described in the National Fuel GasCode,ANSIZ223.1/NFPA54, the International Fuel Gas Code, or applicable local codes.
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