Issue link: https://hi.iaq.net/i/148954
All air distribution joints located outside the pressure boundary shall be sealed. HVAC systems that serve occupiable space shall not be designed to supply air to, or return air from, the garage. HVAC systems that include air handlers or ducts located outside the pressure boundary shall have total air leakage of no more than 6% of total fan flow when measured at 0.1 in. w.c. (25 Pa) using California Title 24 or equivalent. Air handlers and/or ducts shall not be located in a garage unless they are enclosed such that the enclosure meets the separation requirements of Paragraph 6.5.1. 6.6 Minimum Filtration Mechanical space conditioning systems shall be provided with a filter having a designated minimum efficiency of MERV 9 or better when tested in accordance with ANSI/ASHRAE Criterion 52.2, Method of Testing General Ventilation Air-‐Cleaning Devices for Removal Efficiency by Particle Size. If the whole-‐house ventilation system delivers outdoor air to the space conditioning system for tempering and/or distribution, the whole-‐house ventilation system shall be designed such that the outdoor air is filtered to protect the thermal conditioning components. All filters shall be located and installed in such a manner as to facilitate access and regular service by the owner. 6.7 Ventilation System Air Intakes Outdoor air intake openings shall be located a minimum of 10 feet (3048 mm) from any hazardous or noxious contaminant, such as combustion and plumbing vents, chimneys, streets, alleys, parking lots and loading docks. Where an exiting source of contaminant is located within 10 feet (3048 mm) of an intake opening, such opening shall be located a minimum of 3 feet (914 mm) below the exiting contaminant source. The intake shall be placed so that entering air is not obstructed by snow, plantings, or other material, and shall be provided with rodent/insect screens (mesh not larger than 1/4 in. [13 mm]). 6.8 Duct Insulation 6.8.1 Duct Insulation for Whole-‐building Ventilation Systems All outdoor air intake duct shall be insulated with minimum R4.2 duct insulation. In IECC Climate Zones 4 and higher, where an exhaust duct passes through unconditioned space for more than 4 feet, the exhaust duct shall be insulated with minimum R4.2 duct insulation. 6.8.2 Duct Insulation for Local Exhaust Systems In IECC Climate Zones 4 and higher, where an exhaust duct passes through unconditioned space for more than 4 feet, the exhaust duct shall be insulated with minimum R4.2 duct insulation. 6.9 Building Enclosure In IECC Climate Zones 3 and lower, no Class II or lower vapor retarder materials shall be installed on the interior wall or ceiling surfaces to impede drying to the conditioned space. 6.9 Exhaust Make-‐up Air