AIR FOR COMBUSTION AND VENTILATION
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DETERMINING AIR FLOW FOR HEATER LOCATION
Determining if You Have a Confined or Unconfined Space
Use this worksheet 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 20 ft. (length) x 16 ft. (width) x 8 ft. (ceiling height) =
2560 cu. ft. (volume of space)
If additional ventilation to adjoining room is supplied with grills or open- ings, add the volume of these rooms to the total volume of the space.
2.Divide the space volume by 50 cubic feet to determine the maximum Btu/Hr the space can support.
______(volume of space) ÷ 50 cu. ft. = (Maximum Btu/Hr the space can sup- port)
Example: 2560 cu. ft. (volume of space) ÷ 50 cu. ft. = 51.2 or 51,200 (maximum Btu/Hr the space can sup- port)
3.Add the Btu/Hr of all fuel burning ap- pliances in the space.
Total | = ____ Btu/Hr |
Example: |
|
|
|
Gas water heater | 40,000 | Btu/Hr | |
20,000 | Btu/Hr | ||
|
|
|
|
Total | = | 60,000 | Btu/Hr |
*Do not include
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)
60,000 Btu/Hr (actual amount of Btu/Hr used)
The space in the above example is a con- fined 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 worksheet, adding the space of an adjoining room. If the extra space provides an unconfined space, remove door to adjoining room or add ventila- tion grills between rooms. See Ventila- tion Air From Inside Building.
B.Vent room directly to the outdoors. See Ventilation Air From Outdoors, page 5.
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: If the area in which the heater may be oper- ated is smaller than that defined as an unconfined space, provide adequate combustion and venti- lation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1, 1992, Section 5.3 or applicable local codes.
VENTILATION AIR
Ventilation Air From Inside Building
This fresh air would come from an adjoining unconfined space. When ventilating to an adjoining unconfined space, you must pro- vide 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 2 page 5). You can also remove door into adjoining room (see option 3, Figure 2). Follow the National Fuel Gas Code NFPA 54/ANSI Z223.1, Sec- tion 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.
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