449.3.6 Heating, Ventilating and Air-Conditioning Systems
(Reference The Guidelines for other requirements.)
Air-handling equipment shall be installed exterior of the building, to include the roof, in a designated equipment room(s), or in a space(s) located in an attic(s). If the equipment serves only one room, it may be located above the ceiling and shall be accessible through an access opening in accordance with this code. Access panels are not required for lay-in ceiling installations, provided the service functions are not obstructed by other above-ceiling construction, such as electrical conduits, piping, audio visual cabling and like equipment components or supports.
All new hospital, outpatient surgery and cardiac catheterization facility construction shall have completely ducted air-supply, return, outside air and exhaust systems. In hospital buildings with multiple uses, tenants or occupancies, located on a separate floor or floors within the building, or located in a medical office building, only the licensed health care areas where invasive procedures, as defined by The Guidelines, are performed shall be required to be served by separate ducted mechanical air-supply, return and exhaust systems.
In new construction, horizontal offsets of duct system risers penetrating more than one floor shall not be allowed.
Flexible ducts shall be listed and labeled to the UL181 Standard for Factory-Made Air Ducts and Air Connectors and shall be Class 0 or Class 1. Flexible ducts shall meet the following additional performance rating criteria:
The duct shall have a minimum rated air velocity of 4,000 feet per minute, a minimum positive pressure rating of 4 inches water gauge, and a minimum negative pressure rating of 1 inch water gauge.
The outer vapor barrier shall have a perm rating not greater than 0.05 perms when tested in accordance with ASTM E 96, Procedure A.
Variable air volume systems shall not be permitted for use in surgical departments, obstetrical departments, laboratories, isolation rooms and critical care units and rooms.
Filter housing frame blank-off panels shall be permanently attached to the frame, constructed of rigid materials and have sealing surfaces equal to or greater than the filter media installed in the filter frame. All joints between the blank-off panels, filter housing frames and filter support structure shall be caulked airtight.