What are the components of an exhaust system?

expert EXPERT April 26, 2007

These are typically quiet fans, often located in bathrooms or kitchens, since these are the sources of concentrated pollutants, including moisture and odors. The fans are typically designed to operate continuously and are sometimes two-speed or multi-speed fans. There is usually a manual control, and sometimes an automatic control such as a dehumidistat. There may also be a timer.

The fans are connected to ductwork and discharge outside the building. The outlets are typically four to eight inches above grade, and about six feet away from other mechanical inlets for the building. We don't want to exhaust air and then pull it right back into the house.

The discharge point of the exhaust system should not be under decks or in garages, crawlspaces or other confined areas. The duct system is sealed at the wall or ceiling penetration to prevent air leakage and keep moisture out of the building. The terminations are hooded to keep snow, wind and rain out of the duct. There's typically a flap to keep out drafts as well as animals, birds and insects when the system is not operating.