Do Air Conditioners Bring in Fresh Air From Outside?
Understanding Where Your Air Comes From
It is often asked, 'do air conditioners bring in fresh air from outside?' With more and more reports published every year about indoor air quality concerns and the associated health risks, it is understandable that consumers are trying to learn out exactly how their air conditioner works and where their air comes from.
The short answer regarding whether your AC brings in fresh air from outside is no, it does not bring in fresh air from outside, but that is not the complete answer. Simply put, air conditioners do not by default bring in any fresh air from outside. But this isn't the whole picture and is not always true. To grasp from where your air comes and what affects its quality, it's essential to understand the mechanics behind the entire process.
How Does an AC Work and Where Does My Air Come From?
There are several types of air conditioners and heaters. Some homes have a straight cool system with electric heat, which means it has the air conditioning function for cooling but heats only by electric heat strips. A heat pump, alternatively, can reverse its cooling function to heat the home and has electric heat strips as a supplemental source. A furnace uses the same air conditioning function for cooling but uses natural gas or propane for heating. But how does it work and where does the air come from?
Air Conditioners Transfer Temperature, Not Air
Without getting too technical, air conditioners do not transfer air, they transfer temperature. The system's refrigerant, usually Freon or 410A, extracts heat from inside your home and moves it outside through a copper line. That's why warm air blows out of the top of your outside AC condenser when your air conditioner is in cooling mode: it is not moving cold air into your home, it is pulling heat out of it and recirculating the cooler air that remains in your home. When a heat pump switches to heating mode it reverses this cycle, pulling heat from outside and releasing it into your home. In both modes, however, it is simply a transfer of heat.
Some Fresh Air Gets In
While air conditioners are not designed to bring in air from the outside, that doesn't mean they don't. In older homes, fresh air is pulled in through areas lacking proper insulation or that are poorly sealed, like around doors and windows or exterior walls. Through these cracks some fresh air will make it inside and some inside air will seep out.
Fresh Air Vents
On newer homes, however, they are often built so airtight that a fresh air vent is installed. These fresh air vents run directly to your air handler and are sized exactly so that when your HVAC is running it is pulling in some fresh air. This is less a function of the air conditioner and more a design of the home.
Not Designed to Bring in Fresh Air
When you wonder 'do air conditioners bring in fresh air from outside', you can now know that your HVAC unit is actually designed to recirculate the air in your home without bringing any in from outside. This fact is critical to understanding indoor air quality issues and how our homes often steadily recirculate dirty air.
Is the Air in My Home Fresh and Clean?
The air in your home is usually not fresh and clean. In fact, your home's air is often the dirtiest you'll ever breathe. One reason for this is where your air passes through and pulls from sometimes. Attic air, filled with dangerous contaminates like mold, mildew, animal feces, toxic insulation, dust, and other concerning elements can contaminate your home's air system. Poor insulation or damaged duct work can allow dirty attic air to enter your home and ultimately your lungs. This is the leading reason for indoor air quality issues and why consumers are constantly searching for solutions.
How Do You Improve Indoor Air Quality?
Now that you know your AC does not bring in air from outside, it's time to talk about improving the air inside your home. Knowing that this air is continuously recirculating, that means the same contaminates are passing through your duct and blowing back out into your home over and over again until something stops it. Sometimes, that thing that catches a contaminate is your lungs. Your lungs are your body's filter against contaminates, but they aren't as easy to change and clean as the filters you should be using on your air conditioning system.
Air Filters
Every AC is designed to have a simple filter installed. These come in various types such as fiberglass, polyester, washable, pleated, and electrostatic. Generally, homeowners use fiberglass or pleated and are recommended to change them once per month.
Electrostatic Filters
When you want the best of the best, go with electrostatic. These filters have a slight electric charge that produces static. This static electricity pulls in and catches air particles much more efficiently than any other filter type.
UV Lights
Aside from particles in the air, you can also have mold spores and germs circulating. These usually aren't stopped by any type of filter, but they can be killed by a UV light. Most UV lights advertise about 99% effectiveness in killing germs as they pass through your AC's air handler.
Now You Know
In summary, standard air conditioners do not bring in fresh air from outside; instead, they recirculate and cool the indoor air. This process involves drawing in warm air, cooling it through a refrigeration cycle, and redistributing it throughout the space. For fresh air, consider alternatives like opening windows or using ventilation systems designed to introduce outside air. Understanding your AC’s capabilities can help you maintain optimal indoor air quality and comfort.
Concerned About Indoor Air Quality?
Our team cares about the quality of the air you're breathing. If you are concerned as well, give us a call. We'll come out at no cost to assess your home's duct, insulation, and overall air quality condition. There's no cost for an assessment, and estimates are always free.
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