The ductwork in your home is easy to take for granted. It quietly serves its purpose hidden behind walls, above ceilings or running through the attic or basement. But defective ducts can both waste energy and threaten indoor air quality.

How Is Indoor Air Quality Threatened by Ducts?

  • Dirty air can be sucked into leaky ductwork as it runs through unconditioned parts of the house. This can happen in a crawl space, attic, basement or wall cavity. Because of negative pressure in the ducts, dirty air will infiltrate them, mix with conditioned air and circulate through your home. Or dirty air might sneak into return ducts and add to the workload of your HVAC system’s air filter.
  • In a properly working forced-air heating and cooling system, the supply and return sides of the duct system should be balanced with equal amount of air. If air on the supply side is escaping through duct leaks or wall cavities that serve as duct runs, it creates negative pressure. Pressure equalizes when outside air rushes into the home through gaps and cracks in the outer envelope. That in-flowing air may come from areas with dirty air, such as a crawl space or attached garage.
  • Backdrafting can occur when a combustion appliance such as a water heater or furnace isn’t properly exhausting carbon monoxide and other toxic gases. These gases may get sucked into ductwork and back into the house as a result of negative air pressure. This can create a potentially lethal situation.
  • Leaky ducts can make your indoor air more humid, as moist outside air is drawn into the ducts from a damp basement or crawl space. This makes your A/C or heat pump work harder to dehumidify the air as part of the cooling process. This contributes to poor indoor air quality.

For more information on how properly designed and maintained ducts can improve indoor air quality in your Northern Virginia home, please contact the pros at One Hour Heating & Air Conditioning® of Northern Virginia.