What is the required discharge location for air from mechanical exhaust systems?

The required discharge location for air from mechanical exhaust systems is outdoors. This is because exhausting air outside prevents the recirculation of stale or contaminated air within the building, which is essential for maintaining indoor air quality. Proper outdoor discharge allows for the dispersal of potentially harmful pollutants, moisture, and odors generated from the mechanical processes inside the building.

Discharging air into a building would lead to a buildup of pollutants and reduce ventilation effectiveness, creating unhealthy indoor conditions. Similarly, venting into a crawl space could promote moisture accumulation and mold growth, which presents further health risks. Directing exhaust into a duct system is not suitable for general exhaust as it can cause the reintroduction of unwanted air back into the living space, circumventing the purpose of exhausting air from areas where air quality is a concern. Therefore, the most effective and compliant method as stipulated in the International Mechanical Code is to exhaust air directly outdoors.