Do HVAC Systems Bring in Fresh Air?

Learn how HVAC systems work and how they can help you bring fresh air into your home.

Do HVAC Systems Bring in Fresh Air?

Most home heating and cooling systems, including forced air heating systems, do not mechanically bring fresh air into the home. In most cases, an HVAC system doesn't introduce fresh air into a building. Your home is heated and cooled by recycling indoor air, and any outside air that enters the building is the result of processes independent of the HVAC system. Although in the design of split system air conditioners, commonly heat pumps, part of your system is located outside your home, it does not absorb outside air.

Outside air is introduced into the system from an inlet that is usually located next to your oven, but which is sometimes its own separate system. Your primary operational purpose of cooling the air in your home is not achieved by moving cold air indoors, but by removing unwanted heat. The fact that air conditioning units do not provide “fresh air” from outside is very useful, especially for those who suffer from pollen allergies. The intake of outside air can carry the potential risk of introducing pollen and particles, which can be very harmful to health.

By recirculating the air that is already present in your room, you can ensure that it is virtually free of pollen and dust, as your air conditioning unit filters it repeatedly. No, central air conditioners don't draw outside air into the house. Instead, they remove heat and moisture from the air in your home and release cold air inside the house through the duct system. No, air conditioners don't allow fresh outside air to enter.

That's not how they were designed. What actually happens is that the air conditioner uses a fan to draw air into the unit and disperse it through a structure. Adding fresh air to a heating or cooling system achieves two primary indoor air quality objectives: pressurizing a building and increasing indoor air quality by diluting polluted or stale indoor air. Adding a fresh air intake to most systems is usually a simple and relatively inexpensive proposition.

Your oven has burners that generate flue gases. These gases pass to the heat exchanger. As the air flows over them, it heats up and then flows through the air ducts to the different rooms of your home. Once cooled air is introduced into the house from the duct system, it is circulated through the house through the return duct systems back to the air conditioner.

However, cracks and leaks in HVAC ducts can allow outside air to enter the interior, so regular maintenance of your HVAC system is essential to ensure that all filters are working properly and that there are no inefficiencies in air transfer. While your air conditioning systems have built-in air filters, you still need to take some additional steps to ensure that you and your loved ones breathe quality air. Even during the warmer seasons, when you need cool air, the heating system will work together with your air conditioning unit to produce cool air. Known as dedicated outdoor air systems (DOAS), DOAS systems will use parallel ventilation of the indoor and outdoor units to circulate air in and out of your home.

The location of the fresh air inlet of the air conditioner may vary depending on the manufacturer of the appliances and the exclusive layout of your home. While fresh air is generally considered a good thing, there are several benefits to having HVAC systems that don't circulate outside air freely, as Covington One Hour Air points out. If you want to bring fresh air into your home, do so through controlled means, such as opening a window to allow the breeze to circulate. In addition to ensuring that your unit works properly, you can also enjoy clean and fresh air inside your home.

Central air conditioning units derive their air supply from the home's indoor air that is supplied to the air conditioning unit through the duct system.