OWNER'S MANUAL
AIR FOR
COMBUSTION AND
VENTILATION
Continued
DETERMINING
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 firebox 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) |
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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. |
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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 support)
Example: 3168 cu. ft. (volume of space) .'- 50 cu. ft. = 63.3 or 63,300 (maximum Btu/Hr the space can support)
3.Add the Btu/Hr of all fuel burning appliances in the space.
firebox | Btu/Hr |
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Gas water | heater* | Btu/Hr | Example: |
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Gas furnace | Btu/Hr | Gas water | heater | 40,000 | Btu/Hr | ||
Vented | gas heater | Btu/Hr | firebox with log heater + | 39,000 | Btu/Hr | ||
Gas firebox logs | Btu/Hr | Total |
| 79,000 | Btu/Hr | ||
Other | gas appliances* + | Btu/Hr |
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Total |
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*Do not include
4.Compare the tnaximum Btu/Hr the space can support with the actual amount of Btu/Hr used.
Btu/Hr (actual amount of Btu/Hr used)
Example: 63,300 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 support. Yon 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 adjoin- ing room or add ventilation grills between rooms. See Ventilation Air From Inside Building, page 6.
B.Vent room directly to the outdoors. See Ventilation Air From Outdoors, page 6.
C.Install a lower Btu/Hr fireplace, if lower
"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.
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_lb WARNING: If the area In which the firebox end gas log heater may be operated is smeller than that defined as I an unconfined space or If the building Is of unusually tight construction, provide adequate combustion and I ventilation air by one of the methods described in the National Fuel Gas Code, ANS Z223.1, 1992, Section 5.3 or eppllceble local codes.
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