Choosing The Right Air Filter For Your Furnace

One of the best ways to keep the air in your home clean is to use high-efficiency furnace filters (rated MERV 11 or higher) and to change them regularly.

While changing your filter 3-4 times a year is typically sufficient, you may need to change more frequently if you are in an area that has poor air quality – such as areas impacted by a wildfire. People with asthma and allergies may also find that they need to change their filters more frequently.

When your air filter becomes too dirty, airflow is restricted and your HVAC system has to work extra hard to circulate air through your house. This could result in higher energy costs and an overworked HVAC system. In addition, changing your filter regularly can:

See the difference between a dirty (removed after Camp Fire wildfire) and clean filter below:

What to Look For in a New Filter

To filter the most particulates out of your indoor air, Hayward Score recommends buying high-quality air filters. Depending on the manufacturer, look for the following ratings:

MERV Ratings

A MERV 11 filter, or its equivalent will remove smoke particulates in addition to pet dander, mold spores, pollen, and household dust. A MERV 13 filter, or its equivalent, will also remove bacteria and virus carriers.

If you use filters above MERV 13 or its equivalent, you should have a Heating/Cooling professional evaluate the efficiency of your system.

A Few Last Tips

If you want to eliminate odors, like a smoke smell, you need a filter with charcoal. These filters may need to be replaced more frequently than your regular filter.

If you want to make use of your air filter even when your furnace is not running, you can turn the thermostat to the “Fan” setting, if that feature is available on your system. This will turn on your air handler and move air through your ducts and air filter. Remember, turn off the fan when you don’t need it.

There may be other systems that have filters in your home that may have been impacted by the fire. “Fresh air” ventilation systems, HRV or ERV (brings in outdoor air and removes indoor air), have filters in the unit and/or at the outdoor air intake. Even some supply only ventilation installations, (fans that bring outdoor in into your Heating/ Cooling system), can have a filter at the outdoor air intake. Always use the manufacturers recommended filters.

Last tip! When replacing old filters you should place them in a garbage bag to transport them to the trash so you don’t spread dust and pollutants!

Joe Medosch
Joe Medosch
Joe Medosch has almost 30 years of experience as a contractor and 10 years as a master trainer with expertise in home performance, particularly in health and energy-efficiency. His proficiency includes building science & diagnostics and Indoor Air Quality (IAQ) assessments. He has served on numerous committees developing industry standards including: RESNET Standard 380, Equipment Sub-Committee, and BPI multifamily standards development.
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