- The appliance is a direct-vent appliance installed in accordance with the conditions of the listing and the manufacturer's instructions.
- Vented room heaters, wall furnaces, vented decorative appliances, vented gas fireplaces, vented gas fireplace heaters and decorative appliances for installation in vented solid fuel-burning fireplaces are installed in rooms that meet the required volume criteria of Section 304.5.
- A single wall-mounted unvented room heater is installed in a bathroom and such unvented room heater is equipped as specified in Section 621.6 and has an input rating not greater than 6,000 Btu/h (1.76 kW). The bathroom shall meet the required volume criteria of Section 304.5.
- A single wall-mounted unvented room heater is installed in a bedroom and such unvented room heater is equipped as specified in Section 621.6 and has an input rating not greater than 10,000 Btu/h (2.93 kW). The bedroom shall meet the required volume criteria of Section 304.5.
- The appliance is installed in a room or space that opens only into a bedroom or bathroom, and such room or space is used for no other purpose and is provided with a solid weather-stripped door equipped with an approved self-closing device. All combustion air shall be taken directly from the outdoors in accordance with Section 304.6.
|Iother||=||All appliances other than fan assisted (input in Btu/h).|
|Ifan||=||Fan-assisted appliance (input in Btu/h).|
|ACH||=||Air change per hour (percent of volume of space exchanged per hour, expressed as a decimal).|
ALL AIR FROM OUTDOORS—INLET AIR FROM VENTILATED
CRAWL SPACE AND OUTLET AIR TO VENTILATED ATTIC
(see Section 304.6.1)
ALL AIR FROM OUTDOORS THROUGH VENTILATED ATTIC
(see Section 304.6.1)
ALL AIR FROM OUTDOORS
(see Section 304.6.1)
- The ratio of interior spaces shall be the available volume of all communicating spaces divided by the required volume.
- The outdoor size reduction factor shall be one minus the ratio of interior spaces.
- The minimum size of outdoor opening(s) shall be the full size of outdoor opening(s) calculated in accordance with Section 304.6, multiplied by the reduction factor. The minimum dimension of air openings shall be not less than 3 inches (76 mm).
- Ducts shall be constructed of galvanized steel complying with Chapter 6 of the International Mechanical Code or of a material having equivalent corrosion resistance, strength and rigidity.
Exception: Within dwellings units, unobstructed stud and joist spaces shall not be prohibited from conveying combustion air, provided that not more than one required fireblock is removed.
- Ducts shall terminate in an unobstructed space allowing free movement of combustion air to the appliances.
- Ducts shall serve a single enclosure.
- Ducts shall not serve both upper and lower combustion air openings where both such openings are used. The separation between ducts serving upper and lower combustion air openings shall be maintained to the source of combustion air.
- Ducts shall not be screened where terminating in an attic space.
- Horizontal upper combustion air ducts shall not slope downward toward the source of combustion air.
- The remaining space surrounding a chimney liner, gas vent, special gas vent or plastic piping installed within a masonry, metal or factory-built chimney shall not be used to supply combustion air.
- Combustion air intake openings located on the exterior of a building shall have the lowest side of such openings located not less than 12 inches (305 mm) vertically from the adjoining finished ground level.
In barbershops, beauty shops and other facilities where chemicals that generate corrosive or flammable products, such as aerosol sprays, are routinely used, nondirect vent-type appliances shall be located in a mechanical room separated or partitioned off from other areas with provisions for combustion air and dilution air from the outdoors. Direct-vent appliances shall be installed in accordance with the appliance manufacturer's installation instructions.
Unlisted appliances approved in accordance with Section 301.3 shall be limited to uses recommended by the manufacturer and shall be installed in accordance with the manufacturer's instructions, the provisions of this code and the requirements determined by the code official.
- Overhead heaters where installed not less than 8 feet (2438 mm) above the floor shall be permitted.
- Heating appliances for vehicle repair areas where there is no dispensing or transferring of Class I or II flammable or combustible liquids or liquefied petroleum gas shall be installed in accordance with NFPA 30A.
- The passageway and level service space are not required where the appliance is capable of being serviced and removed through the required opening.
- Where the passageway is not less than 6 feet (1829 mm) high for its entire length, the passageway shall be not greater than 50 feet (15 250 mm) in length.
- The passageway is not required where the level service space is present when the access is open and the appliance is capable of being serviced and removed through the required opening.
- Where the passageway is not less than 6 feet high (1829 mm) for its entire length, the passageway shall not be limited in length.
Permanent ladders installed to provide the required access shall comply with the following minimum design criteria:
- The side railing shall extend above the parapet or roof edge not less than 30 inches (762 mm).
- Ladders shall have rung spacing not to exceed 14 inches (356 mm) on center. The upper-most rung shall be a maximum of 24 inches (610 mm) below the upper edge of the roof hatch, roof or parapet, as applicable.
- Ladders shall have a toe spacing not less than 6 inches (152 mm) deep.
- There shall be a minimum of 18 inches (457 mm) between rails.
- Rungs shall have a minimum 0.75-inch (19 mm) diameter and be capable of withstanding a 300-pound (136.1 kg) load.
- Ladders over 30 feet (9144 mm) in height shall be provided with offset sections and landings capable of withstanding 100 pounds per square foot (488.2 kg/m2). Landing dimensions shall be not less than 18 inches (457 mm) and not less than the width of the ladder served. A guard rail shall be provided on all open sides of the landing.
- Climbing clearance. The distance from the centerline of the rungs to the nearest permanent object on the climbing side of the ladder shall be a minimum of 30 inches (762 mm) measured perpendicular to the rungs. This distance shall be maintained from the point of ladder access to the bottom of the roof hatch. A minimum clear width of 15 inches (381 mm) shall be provided on both sides of the ladder measured from the midpoint of and parallel with the rungs except where cages or wells are installed.
- Landing required. The ladder shall be provided with a clear and unobstructed bottom landing area having a minimum dimension of 30 inches (762 mm) by 30 inches (762 mm) centered in front of the ladder.
- Ladders shall be protected against corrosion by approved means.
- Access to ladders shall be provided at all times.
Catwalks installed to provide the required access shall be not less than 24 inches (610 mm) wide and shall have railings as required for service platforms.
|TYPE OF PROTECTION APPLIED TO
AND COVERING ALL SURFACES OF COMBUSTIBLE
MATERIAL WITHIN THE DISTANCE SPECIFIED AS THE
REQUIRED CLEARANCE WITH NO PROTECTION
[see Figures 308.2(1), 308.2(2), and 308.2(3)]
|WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM
APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS: (inches)
|Allowable clearances with specified protection (inches)|
|Use Column 1 for clearances above appliance or horizontal connector. Use Column 2
for clearances from appliance, vertical connector and single-wall metal pipe.
|Above Col. 1||Sides and rear Col. 2||Above Col. 1||Sides and rear Col. 2||Above Col. 1||Sides and rear Col. 2||Above Col. 1||Sides and rear Col. 2||Above Col. 1||Sides and rear Col. 2|
|1. 31/2-inch-thick masonry wall without ventilated
|2. 1/2-inch insulation board over 1-inch glass fiber or
mineral wool batts
|3. 0.024-inch (nominal 24 gage) sheet metal over 1-inch
glass fiber or mineral wool batts reinforced with wire
on rear face with ventilated airspace
|4. 31/2-inch-thick masonry wall with ventilated airspace||—||12||—||6||—||6||—||6||—||6|
|5. 0.024-inch (nominal 24 gage) sheet metal with
|6. 1/2-inch-thick insulation board with ventilated
|7. 0.024-inch (nominal 24 gage) sheet metal with
ventilated airspace over 0.024-inch (nominal 24 gage)
sheet metal with ventilated airspace
|8. 1-inch glass fiber or mineral wool batts sandwiched
between two sheets 0.024-inch (nominal 24 gage)
sheet metal with ventilated airspace
- Reduction of clearances from combustible materials shall not interfere with combustion air, draft hood clearance and relief, and accessibility of servicing.
- All clearances shall be measured from the outer surface of the combustible material to the nearest point on the surface of the appliance, disregarding any intervening protection applied to the combustible material.
- Spacers and ties shall be of noncombustible material. No spacer or tie shall be used directly opposite an appliance or connector.
- For all clearance reduction systems using a ventilated airspace, adequate provision for air circulation shall be provided as described [see Figures 308.2(2) and 308.2(3)].
- There shall be at least 1 inch between clearance reduction systems and combustible walls and ceilings for reduction systems using ventilated airspace.
- Where a wall protector is mounted on a single flat wall away from corners, it shall have a minimum 1-inch air gap. To provide air circulation, the bottom and top edges, or only the side and top edges, or all edges shall be left open.
- Mineral wool batts (blanket or board) shall have a minimum density of 8 pounds per cubic foot and a minimum melting point of 1500°F.
- Insulation material used as part of a clearance reduction system shall have a thermal conductivity of 1.0 Btu per inch per square foot per hour per °F or less.
- There shall be at least 1 inch between the appliance and the protector. In no case shall the clearance between the appliance and the combustible surface be reduced below that allowed in this table.
- All clearances and thicknesses are minimum; larger clearances and thicknesses are acceptable.
- Listed single-wall connectors shall be installed in accordance with the manufacturer's installation instructions.