Your air conditioner is a breathing machine. It breathes in air from around your home and breathes out cool air. Unfortunately, typical ductwork loses 25-to-40 percent of the air passing through it. That air has to be replaced. That’s where fresh air returns come in.
Fresh air returns add balance
Air in your home moves from high pressure to low pressure. An air conditioner pushes it out at high pressure and draws it back in using low pressure. Balancing those pressures keeps your system efficient. When air is inevitably lost through your duct work, your system draws in air to replace it.
Without fresh air returns, your system pulls air from other sources to re-balance itself. Unfortunately, those sources, such as recessed can lights and soffit vents wind up pulling dirt and debris into your A/C system which gets reticulated throughout your home. The result? More dust. More problems.
A return air is not a fresh air return
After cool air is delivered, it will eventually warm up and need reconditioning. A return air vent allows that warm air to flow back to your air conditioner. It’s best to have a return air duct in every room with a supply register. The more return air vents, the easier it is to balance the pressure in your home.
Fresh air returns improve air quality
A Fresh air return, on the other hand, brings in replacement air from outside. That way your air conditioning system not only equalizes the pressure with “cleaner air,” but eliminates infiltration problems; the return air is filtered, conditioned and then distributed throughout the house.
What about cleaning my ducts?
There’s no research proving routine duct cleaning improves air quality or reduces dust. There is, however, evidence that dirty heating and cooling coils, motors, and air handling units can make your HVAC unit less efficient.
While duct cleaning alone doesn’t seem that necessary, there are some cases where cleaning the HVAC unit and ductwork could be useful. However, changing out all your air filters as needed will typically pre-empt any need for such cleaning.