Multi-Story Passive System

Install intake to pull air from the outdoors, which does not include unconditioned spaces such as attics and crawl spaces that are ventilated with the outdoors

Install intake:

A minimum of 6" from grade;

A minimum of 10' from contaminant sources or exhaust outlets;

Above local snow or flood line;

A minimum of 18" above an asphalt based roof;

Never on a flat roof

Install corrosion resistant screen, louver, or grille material over exterior terminations with a hole size of no less than 1/4" and no greater than 1/2" in any direction

System must contain a backdraft damper between all exterior terminations/intakes that only allows air flow in the desired direction

A system of one or more backdraft dampers shall be installed to isolate each dwelling unit from the common duct when the system is not operating

Intakes/supplies in dwelling units must minimize potential occupant discomfort and/or drafts