{"data":{"id":"us-nyc/n.y.c.-admin.-code-mc-1105","jurisdiction":"us-nyc","citation":"N.Y.C. Admin. Code § MC 1105","heading":"Section MC 1105: Machinery Room, General Requirements","body":"1105.1 Design and construction.\n\nMachinery rooms shall be designed and constructed in accordance with the New York City Building Code and this section.\n\n1105.2 Openings.\n\nDucts and air handlers in the machinery room that operate at a lower pressure than the room shall be sealed to prevent any refrigerant leakage from entering the airstream.\n\n1105.3 Refrigerant detector.\n\nRefrigerant detectors in machinery rooms shall be provided as required by ASHRAE 15.\n\n1105.4 Tests.\n\nPeriodic tests of the mechanical ventilating system shall be performed in accordance with manufacturer's specifications and as required by the Commissioner of the Fire Department.\n\n1105.5 Fuel-burning appliances.\n\nOpen flames that use combustion air from the machinery room shall not be installed in a machinery room.\n\nExceptions:\n\n1. Where the refrigerant is carbon dioxide or water.\n\n2. Fuel-burning appliances shall not be prohibited in the same machinery room with refrigerant-containing equipment or appliances where combustion air is ducted from outside the machinery room and sealed in such a manner as to prevent any refrigerant leakage from entering the combustion chamber, or where a refrigerant vapor detector is employed to automatically shut off the combustion process in the event of refrigerant leakage.\n\n1105.6 Ventilation.\n\nMachinery rooms shall be mechanically ventilated to the outdoors. Location of the mechanical ventilation openings within the machinery room shall be based on the relative density of the refrigerant to air. When compressors or self-contained unit system are housed in a machinery space, other than in a machinery room or plenum, the space shall be ventilated in accordance with the requirements of Section 1105.6.3.\n\nException: Where a refrigerating system is located outdoors more than 20 feet (6096 mm) from any building opening and is enclosed by a penthouse, lean-to or other open structure, natural or mechanical ventilation shall be provided. Location of the openings shall be based on the relative density of the refrigerant to air. The free-aperture cross section for the ventilation of the machinery room shall be not less than:\n\nF = ÖG \n\t\t\t\t\t\t\t\t\t\t\t\t\t \n\t\t\t\t\t\t\t\t\t\t\t\t\t \n\t\t\t\t\t\t\t\t\t\t\t\t\t \n\t\t\t\t\t\t\t\t\t\t\t\t\t(Equation 11-1)\n\nFor SI: F = 0.138ÖG\n\nwhere:\n\nF = The free opening area in square feet (m\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t2\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t).\n\nG = The mass of refrigerant in pounds (kg) in the largest system, any part of which is located in the machinery room\n\n1105.6.1 Discharge location.\n\nThe discharge of the air shall be to the outdoors in accordance with Chapter 5. Exhaust from mechanical ventilation systems shall be discharged not less than 20 feet (6096 mm) from outdoor air intake or openings into buildings and 10 feet (3048 mm) from a fire escape or exterior stair.\n\n1105.6.2 Makeup air.\n\nProvisions shall be made for makeup air to replace that being exhausted. Openings for makeup air shall be located to avoid intake of exhaust air. Supply and exhaust ducts serving the machinery room shall not serve any other area, shall be constructed in accordance with Chapter 5 and shall be covered with corrosion-resistant screen of not less than 1/4-inch (6.4 mm) mesh.\n\nException: The requirement for supply and exhaust ducts to the machinery room to serve no other area shall not apply to a change in the type of refrigerant in a lawfully installed existing refrigerating system being maintained and operated in accordance with these approved installation requirements:\n\n1. Where the replacement refrigerant has a safety classification of Group A1; or\n\n2. Where the replacement refrigerant is R123 and the engineer or architect demonstrates to the satisfaction of the commissioner that providing such air supply and exhaust ducts represents a hardship and that the proposed alternative provides an equivalent level of safety.\n\n1105.6.3 Ventilation rate.\n\nFor other than ammonia systems, the mechanical ventilation systems shall be capable of exhausting the minimum quantity of air both at normal operating and emergency conditions, as required by Sections 1105.6.3.1 and 1105.6.3.2. The minimum required ventilation rate for ammonia shall be 30 air changes per hour in accordance with IIAR2. Multiple fans or multispeed fans shall be allowed to produce the emergency ventilation rate and to obtain a reduced airflow for normal ventilation.\n\n1105.6.3.1 Quantity-normal ventilation.\n\nDuring occupied conditions, the mechanical ventilation system shall exhaust the larger of the following:\n\n1. Not less than 0.5 cfm per square foot (0.0025 m\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t3\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t/s × m\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t2\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t) of machinery room area or 20 cfm (0.009 m\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t3\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t/s) per person.\n\n2. A volume required to limit the room temperature rise to18°F (-7.8°C) taking into account the ambient heating effect of all machinery in the room but not above a maximum temperature of 122°F (50°C).\n\n1105.6.3.2 Quantity-emergency conditions.\n\nUpon actuation of the refrigerant detector required in Section 1105.3, the mechanical ventilation system shall exhaust air from the machinery room in the following quantity:\n\nQ = 100 x ÖG \n\t\t\t\t\t\t\t\t\t\t\t\t\t \n\t\t\t\t\t\t\t\t\t\t\t\t\t \n\t\t\t\t\t\t\t\t\t\t\t\t\t(Equation 11-2)\n\nFor SI: Q = 0.07 x ÖG\n\nWhere:\n\nQ = The airflow in cubic feet per minute (m\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t3\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t/s).\n\nG = The design mass of refrigerant in pounds (kg) in the largest system, any part of which is located in the machinery room\n\n1105.7 Termination of relief devices.\n\nIn addition to the requirements of Section 9.7.8 of ASHRAE 15, pressure relief devices, fusible plugs and purge systems located within the machinery room shall terminate outside of the structure at a location not less than 15 feet (4572 mm) above the adjoining grade level and not less than 20 feet (6096 mm) from any window, ventilation opening or exit.\n\n1105.7.1 Discharge of Group A2, B2, A3 and B3 refrigerants.\n\nDischarge of systems containing Group A2 or B2 refrigerants shall be acceptable to the commissioner. Discharge of systems containing Group A3 or B3 refrigerants shall be subject to the approval of the commissioner and the Commissioner of the Fire Department. Nothing in this section shall be construed to approve the use of Group A3 and B3 refrigerants if otherwise prohibited.\n\n1105.7.2 Certificate of qualification.\n\nDischarge of pressure relief devices, fusible plugs and purge systems for refrigerating systems containing flammable, toxic and highly toxic refrigerants and ammonia shall comply with Section 606 of the New York City Fire Code.\n\n1105.8 Ammonia discharge.\n\nPressure relief valves for ammonia systems shall discharge in accordance with ASHRAE 15.\n\n1105.9 Emergency pressure control system.\n\nPermanently installed refrigeration systems containing more than 6.6 pounds (3 kg) of a refrigerant other than a Group A1 refrigerant shall be provided with an emergency pressure control system in accordance with Sections 1105.9.1 and 1105.9.2.\n\n1105.9.1 Automatic crossover valves.\n\nEach high- and intermediate-pressure zone in a refrigerating system shall be provided with a single automatic valve providing a crossover connection to a lower pressure zone. Such automatic crossover valves shall comply with Sections 1105.9.1.1 through 1105.9.1.3.\n\n1105.9.1.1 Overpressure limit setpoint.\n\nAutomatic crossover valves shall be arranged to automatically relieve excess system pressure to a lower pressure zone if the pressure in a high- or intermediate-pressure zone rises to within 15 psi (108.4 kPa) of the setpoint for pressure-relief devices.\n\n1105.9.1.2 Manual operation.\n\nAutomatic crossover valves shall be capable of manual operation for refrigerating systems containing more than 200 pounds (90.8 kg) of refrigerant.\n\n1105.9.1.3 System design pressure.\n\nRefrigerating system zones that are connected to a higher pressure zone by an automatic crossover valve shall be designed to safely contain the maximum pressure that can be achieved by interconnection of the two zones.\n\n1105.9.2 Automatic emergency stop.\n\nAn automatic emergency stop feature shall be provided in accordance with Sections 1105.9.2.1 and 1105.9.2.2.\n\n1105.9.2.1 Automatic crossover valves.\n\nA refrigerating system equipped with an automatic crossover valve shall be designed, when such valve is activated, to cause all compressors on the affected system to immediately cease operating. Dedicated pressure-sensing devices located immediately adjacent to crossover valves may be used as a means for activating such crossover valve. To ensure that the automatic crossover valve system provides a redundant means of ceasing operation of the compressors in an overpressure condition, high-pressure cutout sensors associated with compressors shall not be used for purposes of activating such crossover valve.\n\n1105.9.2.2 Overpressure in low-pressure zone.\n\nThe lowest pressure zone in a refrigerating system shall be provided with a dedicated means of determining a rise in system pressure to within 15 psi (103.4 kPa) of the zone pressure relief device setpoint. Activation of such overpressure sensing device shall cause all compressors on the effected system to immediately cease operation.\n\n1105.10 Remote control.\n\nA clearly identified switch of the break-glass type shall provide off-only control of the compressors in the machinery room. A second clearly identified switch of the break-glass type shall provide on-only control of the machinery room ventilation fans. Such switches shall be located outside each entrance to the machinery room and as close to the entrance as practicable, except that when an outside location is impracticable, such switches may be located immediately inside the machinery room provided such location is accessible at all times.\n\n1105.11 Emergency signs.\n\nSigns shall comply with the following:\n\n1. Sections 8.11.8 and 11.2.4 of ASHRAE 15.\n\n2. Refrigeration units or systems having a refrigerant circuit containing more than 220 pounds (99.8 kg) of Group A1 or 30 pounds (13.6 kg) of any other group refrigerant shall be provided with approved emergency signs, charts, and labels in accordance with NFPA 704.\n\n1105.12 Storing refrigerant.\n\nThe total amount of refrigerant stored in a machinery room shall be the lesser of: (i) not more than twenty percent of the normal charge in the system; or (ii) not more than 330 pounds (149.7 kg) in addition to the charge in the system and the refrigerant contained in a permanently attached receiver. Refrigerant shall be stored in containers meeting the requirements of the New York City Fire Code.\n\nException: Recovery service containers used for storing refrigerant during periods of system maintenance or replacement may exceed 330 pounds (149.7 kg) provided such containers are securely fixed in position and have pressure relief valves piped to the outside in conformance with this code.","path":["New York City Administrative Code","Title 28","Chapter 8: New York City Mechanical Code"],"source_url":"https://files.amlegal.com/pdffiles/NewYorkCity/Admin/XML.zip","current_through":"Local Law 2026/135 (enacted August 31, 2026)","vintage":"","retrieved_at":"2026-09-06T02:48:57Z","sha256":"0b178a8f6c03f2b01c3720e576cf46209f8ebd6d79b5dcd70ae66ea032e3e62a","source_id":"us-nyc","stale":false,"prev":"us-nyc/n.y.c.-admin.-code-mc-1104","next":"us-nyc/n.y.c.-admin.-code-mc-1106"},"notice":"GroundRules: Original legal text. Not legal advice."}