501.2 Exhaust discharge.
The air removed by every mechanical exhaust system shall be discharged outdoors at a point where it will not cause a nuisance and the air shaft will be located not less than the distances specified in Section 501.2.1.
The air shall be discharged to a location from which it cannot again be readily drawn
in by a ventilating system. Air shall not be exhausted into an attic or crawl space.
Exceptions:
1.Whole-house ventilation-type attic fans shall be permitted to discharge into the attic space of dwelling units having privateattics.
2. Commercial cooking recirculating systems.
501.2.1 Location of exhaust outlets.
The termination point of exhaust outlets and ducts discharging to the outdoors shall be located within the following minimum distances:
1.For ducts conveying noxious, toxic, explosive or flammable vapors, fumes or dusts (including but not limited to exhaust form dry cleaning establishments and spray booths): 30 feet (9144 mm) from property lines; 10 feet (3048 mm) from operable openings into buildings; 6 feet (1829 mm) from exterior walls and roofs; 30
feet (9144 mm) from combustible walls and operable openings into buildings which are in the direction of the exhaust discharge; 10 feet (3048 mm) above adjoining grade. Additional requirements may apply to Hazardous Exhaust Systems; see Section 510.
2. For other product-conveying outlets: 10 feet (3048 mm) from the property lines; 3 feet (914 mm) from exterior walls and roofs; 10 feet (3048 mm) from operable openings into buildings; 10 feet (3048 mm) above adjoining grade; 10 feet from any exterior fire escape, stair, or balcony.
3. For all environmental air exhaust outlets: 3 feet (914 mm) from property lines; 3 feet (914 mm) from operable openings into buildings for all occupancies other than Group U, and 10 feet (3048 mm) from mechanical air intakes. Such exhaust outlets shall not be considered hazardous or noxious.
4. Exhaust outlets and openings serving structures in flood hazard areas shall be installed in accordance with Appendix G of the New York City Building Code.
5. For specific systems see the following sections:
5.1. Clothes dryer exhaust, Section 504.4.
5.2. Kitchen hoods and other kitchen exhaust equipment, Sections 506.3.12, 506.4 and 506.5
5.3. Dust stock and refuse conveying systems, Section 511.
5.4. Subslab soil exhaust systems, Section 512.4.
5.5. Smoke control systems, Section 513.10.3
5.6. Refrigerant discharge, Section 1105.7.
5.7. Machinery room discharge, Section 1105.6.1.
6. In Occupancy Groups R-2 and R-3 each dwelling unit may be individually exhausted directly to the outdoors with a dedicated, exhaust fan and shall comply with the following:
6.1. The exhaust system for the kitchen and the toilet/baths may be combined to the inlet of a continuously operated single fan, provided such exhaust system serves only one dwelling unit.
6.2.The dedicated exhaust from each dwelling unit shall be directed away from any window serving the same dwelling unit from which the exhaust is taken, and in addition, such exhaust opening shall terminate at least:
6.2.1. Two feet (610 mm) from any operational window
or door serving the same dwelling unit.
6.2.2. Three feet (1219 mm) from any operational window or door serving an adjoining dwelling unit.
6.2.3. Three feet (1219 mm) from any operational window or door serving another occupancy group in the same building.
6.2.4. Ten feet (3048 mm) from any outdoor air intake opening.
6.2.5. Ten feet (3048 mm)
above the public sidewalk adjoining the same building.
6.2.6. All other minimum distances prescribed in Items 1 through 5 of Section 501.2.1 shall be satisfied.
501.2.1.1 Exhaust discharge. Exhaust air shall not be directed onto walkways.
501.2.2 Exhaust opening protection. Exhaust openings that terminate outdoors shall be protected with corrosion-resistant screens, louvers or grilles. Openings in screens, louvers
and grilles shall be sized not less than ¼ inch (6 mm) and not larger than ½ inch (13
mm). Openings shall be protected against local weather conditions. Outdoor openings located in exterior walls shall meet the provisions for exterior wall opening protective in accordance with the New York City Building Code.
501.2.2.1 Wind-driven rain rating. All exterior louvers for building exhaust systems shall either:
Receive an A rating according to AMCA Standard 550 for wind-driven rain penetration for a 50 mile per hour (80.4 km/h) wind velocity with a rainfall rate of 8 inches (203 mm) per hour; or
2. Be installed on a plenum configured to intercept any wind-driven rain penetrating the louver and to prevent the rain from entering the building ductwork system. Such plenum shall be waterproofed and equipped with a drainage system to
convey water penetrating the louver to storm or sanitary drains.
501.3 Pressure equalization.
Mechanical exhaust systems shall be sized to remove the quantity of air required by this chapter to be exhausted. The system shall operate when air is required to be exhausted. Where mechanical exhaust is required in a room or space in
other than occupancies in R-3, such space shall be maintained with a neutral or negative pressure. If a greater quantity of air is supplied by a mechanical ventilating supply system than is removed by a mechanical exhaust for a room, adequate means shall be provided
for the natural or mechanical exhaust of the excess air supplied. If only a mechanical exhaust system is installed for a room or if a greater quantity of air is removed by a mechanical exhaust system than is supplied by a mechanical ventilating supply system for a room, adequate makeup air consisting of supply air, transfer air or outdoor air shall be provided to satisfy the deficiency. The calculated building infiltration rate and openable area shall not be used to satisfy the requirements of this section.
501.4 Ducts.
Where exhaust duct construction is not specified in this chapter, such construction shall
comply with Chapter 6.
501.5 Independent system required.
1.Single or combined mechanical exhaust systems from bath, toilet, urinal, locker, service sink closets and similar rooms shall be independent of all other exhaust systems, except as permitted in Section 501.2.1.
2. A separate grease duct system shall be provided for each Type I hood except as provided in Section 506.3.5.
3. Hazardous exhaust systems shall be independent of other types of exhaust systems as provided in Section 510.
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