1105.6.2 Makeup air.
MC § 1105.6.2
Provisions 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. Exception: 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: 1. Where the replacement refrigerant has a safety classification of Group A1; or 2. 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.
