The National Fuel Gas Code defines a confined space as a space whose volume is less than 50 ft 3 per 1,000 BTU/Hr (4.8 m3 per kw) of the aggregate input rating of all appliances installed in that space and an unconfined space as a space whose volume is not less than 50 ft 3 per 1,000 BTU/Hr (4.8 m3 per kw) of the aggregate input rating of all appliances installed in that space. Rooms communicating directly with the space in which the appliances are installed, through openings not furnished with doors, are considered a part of the unconfined space.
Unusually tight construction is defined as construction where:
a. Walls and ceilings exposed to the outside atmosphere have a continuous water vapor retarder with a rating of one perm or less with openings gasketed or sealed, and
b.Weather stripping has been added on oper- able windows and doors, and
c.Caulking or sealants are applied to areas such as joints around window and door frames, between sole plates and floors, between
Use the following equations to determine if you have a confined or unconfined space.
1.Determine the volume of space — ft 3.
Length x Width x Height = _____ ft 3 (Include adjoining rooms with doorless passageways or ventilation grills between rooms).
Example: 24' (L) x 16' (W) x 8' (H) = 3072 ft 3
2.Divide the volume of space by 50 ft 3 to determine the maximum BTU/Hr the space can support.
(volume of space – ft 3)/ 50 ft 3 = (Maximum BTU/Hr the space can support)
Example: 3072 ft 3 / 50 ft 3 = 61.44
or 61,440 BTU/Hr the space can support.
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3.Add the BTU/Hr of all the fuel burning appli- ances in the space.
________ | BTU/Hr | |
Gas appliance #1* | ________ | BTU/Hr |
Gas appliance #2 | +________ | BTU/Hr |
Total =________ | BTU/Hr | |
Example: |
|
|
26,000 | BTU/Hr | |
Gas appliance #1 | 40,000 | BTU/Hr |
(water heater) |
|
|
Total = 66,000 | 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
(max. the space can support)
_________ BTU/Hr
(actual amount of BTU/Hr used)
Example:
61,440 BTU/Hr
(max. the space can support)
66,000 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.
WARNING
If the area in which the heater may be operated is smaller than that defined as an unconfined space, provide adequate combustion and ventilation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1 1992, Section 5.3 or applicable local codes.
NOTE: DIAGRAMS & ILLUSTRATION ARE NOT TO SCALE.
Your options are:
a.Rework equations adding the space of adjoin- ing room(s). If the extra volume provides an unconfined space, then remove door or add ventilation grills between rooms. Refer to National Fuel Gas Code, ANSI Z223.1 1992, Section 5.3.
b.Vent room directly to the outdoors. Refer to National Fuel Gas Code, ANSI Z223.1 1992, Section 5.3.
c.Install a lower BTU/Hr heater, such as a21,000 BTU/Hr, to make the area an unconfined space.
If the actual BTU/Hr used is less than the maximum BTU/Hr the space can support, then the space is an unconfined space. You will need no additional fresh air ventilation for an unconfined space.
COLD CLIMATE INSULATION
For cold climate installations, seal all cracks around the appliance with noncombustible material and wherever cold air could enter the room. It is especially important to insulate outside cavities between studs and under floor on which the appliance rests, if floor is above ground level. Gas line holes and other openings should be caulked with high temperature caulk or stuffed with unfaced fiberglass insulation. If the fireplace is being installed on a cement slab, in cold climates, a sheet of plywood or other raised platform can be placed underneath to prevent conducting cold up into the room. It also helps to sheetrock inside surfaces and tape for maximum air tightness and caulk firestops.
NEW YORK CITY, NEW YORK (MEA)
Installation of these fireplaces are approved for installation in New York City in the US state of New York.