• Cleaner Air Know-How: HVAC 101

    Familiarizing yourself with some HVAC basics can help maximize the comfort in your home.

    Familiarizing yourself with some HVAC basics can help maximize the comfort in your home.

    • How HVAC systems work

      If you have a central heating, ventilation and air conditioning (HVAC) system, it could be dubbed the heart of your home, with ductwork acting as arteries to provide thermal comfort throughout various rooms. It’s an intricate set of equipment that moves air between indoor and outdoor areas, filtering and circulating cleaner air to you and your family.

      Here’s a rundown of parts and important things to know to care for your equipment.

      What to know about HVAC system components

      (For helpful visual diagrams of how it all works together, check out the U.S. Department of Energy’s comprehensive guides to home cooling (PDF, 1.79 MB) and heating (PDF, 1.14 MB).)

      Air handling unit:

      This is the main device inside your house that contains the heating and cooling technologies. It distributes hot or cool air through ducts..

      Air ducts:

      Moves air from the furnace or air conditioner to the rooms in your house.


      Circulates air inside your home. You may recognize this component as you install a new Filtrete™ Filter: our packaging includes an airflow arrow that should point toward the AC/heating blower.

      Evaporator coil:

      Located on top of the furnace, this mechanism cools the air.


      Ensures proper airflow and protects your equipment. Depending on the filtration level, the filter may be able to capture a variety of unwanted air particles, such as dust, pollen, pet dander, bacteria and viruses, improving your indoor air quality. Filters will either be installed in your furnace or in a wall or ceiling, depending on the type of HVAC system in your home.

      Condenser coil:

      Part of the air conditioning unit, this removes heat from the system.

      Condenser fan:

      Generates air current on an outdoor air conditioning unit.


      Supplies an increased pressure of air or gas.

      Refrigerant filled tubing:

      Moves refrigerant through the air conditioning mechanisms between the indoor evaporator coil and the outdoor condenser unit.

      What you can do for HVAC maintenance

      A good rule of thumb is to have a professional technician inspect the unit at least once or twice a year, in the spring and/or in the fall before the unit’s hardest-working seasons. This can help ensure it’s running optimally and prevent costly repairs down the road. (Read here for questions to ask your HVAC professional.)

      Don’t forget to do your homework in between visits from your HVAC pro. Change your HVAC filter regularly. We recommend you replace your Filtrete™ Filters at least every 90 days if it’s 1” or every 12 months if you have 4” or 5”. This helps provide optimal performance for your HVAC system and desired airborne particle capture.