- In rooms other than those used for sleeping purposes, direct-vent appliances that obtain all combustion air directly from the outdoors and installed in accordance with the conditions of the listing and the manufacturer's instructions.
- In rooms other than those used for sleeping purposes, 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 that are installed in rooms that meet the required volume criteria of Section 304.5.
- In rooms other than those used for sleeping purposes, appliances installed in an enclosure in which all combustion air is taken from the outdoors, in accordance with Section 304.6. Access to such enclosure shall be through a solid weather-stripped door, equipped with an approved self-closing device.
Exception: Type 1 clothes dryers that are provided with makeup air in accordance with Section 614.5.
Exception: Combustion, ventilation, and dilution air shall be obtained solely from the outdoors for fuel-burning appliances with an input greater than 350,000 Btu/h.
For appliances other than fan-assisted, calculate volume using Equation 3-1.
For fan-assisted appliances, calculate volume using Equation 3-2.
|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
For purposes of this calculation, an infiltration rate greater than 0.60 ACH shall not be used in Equations 3-1 and 3-2.
Where communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of not less than 1 square inch per 2,000 Btu/h (1100 mm2/kW) of total input rating of all appliances in the enclosure [see Figure 304.6.1(3)].
FIGURE 304.6.1(1) ALL AIR FROM OUTDOORS—INLET AIR FROM VENTILATED CRAWL SPACE AND OUTLET AIR TO VENTILATED ATTIC (see Section 304.6.1)
FIGURE 304.6.1(2) ALL AIR FROM OUTDOORS THROUGH VENTILATED ATTIC (see Section 304.6.1)
FIGURE 304.6.1(3) ALL AIR FROM OUTDOORS (see Section 304.6.1)
FIGURE 304.6.2 SINGLE COMBUSTION AIR OPENING, ALL AIR FROM THE OUTDOORS (see Section 304.6.2)
- 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).
Exception: Operable louvers shall be interlocked with the appliance so that they are proven to be in the full open position prior to main burner ignition and during main burner operation. Means shall be provided to prevent the main burner from igniting if the louvers fail to open during burner startup and to shut down the main burner if the louvers close during operation.
- Be of galvanized steel complying with Chapter 6 of the New York City Mechanical Code or of equivalent corrosion-resistant material approved for this application.
Exception: Within dwelling units, unobstructed stud and joist spaces shall not be prohibited from conveying combustion air, provided that not more than one required fireblock is removed.
- Have a minimum cross-sectional dimension of 3 inches (76 mm).
- Terminate in an unobstructed space allowing free movement of combustion air to the appliances.
- Have the same cross-sectional areas as the free area of the openings to which they connect.
- Serve a single appliance enclosure.
- 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.
- Not be screened where terminating in an attic space.
- Not slope downward toward the source of combustion air, where serving the upper required combustion air opening.
- Be constructed so that the remaining space surrounding a chimney or chimney liner, installed within a masonry, metal or factory-built chimney cannot be used to supply combustion, ventilation and dilution air, except for direct vent appliances designed and installed in accordance with the equipment manufacturer's instructions and listing.
Exception: Elevation of the ignition source is not required for appliances that are listed as flammable vapor ignition resistant.
Exception: This section shall not apply to appliance installations complying with Section 305.4.
- The requirements of this section shall not apply where the appliances are protected from motor vehicle impact and installed in accordance with Section 305.3 of this code and NFPA 30A.
- Appliances installed in repair garages shall be separated from repair areas by walls or partitions, floors, or floor ceiling assemblies that are constructed so as to prohibit the transmission of vapors and having a fire-resistance rating of not less than 1 hour, and that have no openings in the wall separating the repair area within 8 feet (2438 mm) of the floor. Wall penetration shall be firestopped. Air for combustion purposes shall be obtained from the outdoors. The heating room shall not be used for the storage of combustible materials.
- Heating appliances for vehicle repair areas where there is no dispensing or transferring of Class I or Class II flammable or combustible liquids or liquefied petroleum gas shall be installed in accordance with NFPA 30A.
- 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.
Exception: Within a dwelling unit, appliances installed in a compartment, alcove, basement or similar space shall be provided with access by an opening or door and an unobstructed passageway measuring not less than 24 inches (610 mm) wide and large enough to allow removal of the largest appliance in the space, provided that a level service space of not less than 30 inches (762 mm) deep and the height of the appliance, but not less than 30 inches (762 mm), is present at the front or service side of the appliance with the door open.
- 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 unobstructed and not less than 6 feet (1829 mm) high and 22 inches (559 mm) wide 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 12 inches (305 mm) on center.
- Ladders shall have a toe spacing not less than 7 inches (178 mm) deep.
- There shall be a minimum of 18 inches (457 mm) between rails.
- Rungs shall have a minimum diameter of 0.75-inch (19 mm) and shall be capable of withstanding a 300-pound (136.1 kg) load.
- Where a cage, well or ladder safety device is provided, ladders over 20 feet (6096 mm) in height shall be provided with landing platforms for each 30 feet (9144 mm) of height. Where a cage, well or ladder safety device is not provided, ladders over 20 feet (6096 mm) in height shall be provided with landing platforms for each 20 feet (6096 mm) in height. Landings shall be capable of withstanding a load of 100 pounds per square foot (488.2 kg/m2). Landing dimensions shall be not less than 30 inches (762 mm) and not less than 24 inches (610 mm) in width. A guardrail and toeboard shall be provided on all open sides of the landing.
- Where ladder extensions are installed the side rails of through or side-step ladder extensions shall extend 31/2 feet (305 mm) above the parapets and landings. For through ladder extensions, the rungs shall be omitted from the extensions and shall have not less than 18 inches (457 mm) nor more than 24 inches (610 mm) of clearance between rails. For side-step or offset fixed ladder sections, at landings, the side rails and rungs shall be carried to the next regular rung beyond or above the 31/2 (305 mm) feet minimum.
- Ladders shall be protected against corrosion by approved means.
- Catwalks installed to provide the required access shall be not less than 24 inches wide (610 mm) and shall have railings as required for service platforms.
Exception: An auxiliary drain pan shall not be required for appliances that automatically shut down operation in the event of a stoppage in the condensate drainage system.
TABLE 308.2a through k REDUCTION OF CLEARANCES WITH SPECIFIED FORMS OF PROTECTION
| 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 |
| Sides |
| Above |
| Sides |
| Above |
| Sides |
| Above |
| Sides |
| Above |
| Sides |
| 1. 31/2-inch-thick masonry wall without ventilated air- |
| 2. 1/2-inch insulation board over 1-inch glass fiber or |
mineral wool batts
| 3. 0.0296 (No. 22 gauge) galvanized 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 air- |
| 5. 0.024-inch (nominal 24 gage) sheet metal with ventilated |
| 6. 1/2-inch thick insulation board with ventilated air- |
| 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
|For SI: 1 inch = 25.4 mm, °C = [(°F - 32)/1.8], 1 pound per cubic foot = 16.02 kg/m3, 1 Btu per inch per square foot per hour per °F = 0.144 W/m2 K.|
|a. Reduction of clearances from combustible materials shall not interfere with combustion air, draft hood clearance and relief, and accessibility of servicing.|
|b. 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.|
|c. Spacers and ties shall be of noncombustible material. No spacer or tie shall be used directly opposite an appliance or connector.|
|d. 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)].
|e. There shall be at least 1 inch between clearance reduction systems and combustible walls and ceilings for reduction systems using ventilated airspace.|
|f. 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.|
|g. 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.|
|h. 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.|
|i. 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.|
|j. All clearances and thicknesses are minimum; larger clearances and thicknesses are acceptable.|
|k. Listed single-wall connectors shall be installed in accordance with the terms of their listing and the manufacturer's installation instructions.|
|"A" equals the reduced clearance with no protection.|
|"B" equals the reduced clearance permitted in accordance with Table 308.2. The protection applied to the construction using combustible material shall extend far enough in each direction to make "C" equal to "A."|
FIGURE 308.2(1) EXTENT OF PROTECTION NECESSARY TO REDUCE CLEARANCES FROM GAS EQUIPMENT OR VENT CONNECTIONS
FIGURE 308.2(2) WALL PROTECTOR CLEARANCE REDUCTION SYSTEM
FIGURE 308.2(3) MASONRY CLEARANCE REDUCTION SYSTEM