Location of air inlet in distribution box

Air inlets in a distribution box should be positioned to ensure unobstructed airflow, away from contamination sources, and connected directly to the air handler or ventilation system.Proper Placement GuidelinesAir inlets are typically located on the return side of the air handler or within the distribution box to draw in fresh or recirculated air efficiently. The inlet should have a direct, short path to the air handler, HRV, or ERV, minimizing bends, sagging, or kinks in the ductwork to reduce airflow resistance and maintain system efficiency .Distance from Contamination SourcesMaintain at least 10 feet from known contamination sources such as exhaust vents, dryer vents, kitchen hoods, plumbing vents, or vehicle exhaust .For wall-mounted inlets, ensure a minimum of 3 feet away from dryer exhausts or roof vent terminations .Inlets should not draw air from garages, crawlspaces, attics, or adjacent dwelling units to prevent contamination .Height and OrientationInstall inlets at least 2 feet above grade or above the roof deck to avoid debris and water entry .In some cases, placing the inlet at the gable end of the house is easier than lifting it off the roof 2–4 feet .Use a louvered damper for ventilation inlets to control airflow while preventing debris entry; mesh screens can be used for general protection but are not recommended for dryer vents .Connection to Distribution BoxThe inlet duct should be sealed to the air handler or distribution box using mechanical fasteners and metal tape or mastic to prevent leaks .Ensure the duct is supported adequately to prevent sagging, which can reduce airflow efficiency . By following these guidelines, the air inlet will provide clean, unobstructed airflow to the distribution system, maintain indoor air quality, and optimize HVAC performance .