ABOUT SUPPLY VENTILATION

Keeping Out Contaminants

Supply ventilation systems have two advantages over exhaust ventilation:

• Because the interior of the house is slightly pressurized, contaminants from the garage, basement and attic are less likely to enter the house. Back-drafting of combustion appliances is also less of a risk.
• Before it is introduced inside, fresh air can be filtered and dehumidified to remove pollen, dust, or other contaminants, potentially improving occupant comfort.
• Existing Ductwork or Dedicated Ductwork?

  The most common type of supply ventilation system uses a home’s existing forced-air ductwork to distribute fresh ventilation air. This system, called a central-fan-integrated supply ventilation system, requires a passive duct to bring fresh outdoor air to the furnace’s return air plenum. (To learn more about central-fan-integrated supply ventilation systems, see “More About Supply Ventilation,” below.)

  More rarely, a supply ventilation system has its own dedicated ductwork. In that case, a remote-mounted supply fan is ducted to grilles in the living room and bedrooms.