When Should I Change My Air Conditioner's Air Filter at Home?

February 26, 2015

Want the short answer? Read our FAQ on "How often to change the air filter".  

Every once in a while we’re asked what is the most important thing that Columbia area homeowner's can do to protect their air conditioning and heating system between their scheduled tune-ups? Our advice is simple; remember to change the heating and air conditioning air filter. Replacing furnace and return air filters is critical to the proper performance of your HVAC system, in addition to your home's air quality. Research suggests that indoor air pollution is one of the top five environmental health risks? You probably don’t consider it as you sit and watch TV, but this is the air you breathe day and night. Changing the air filters is not all that hard for most Columbia homeowners, but there are usually two hurdles to actually accomplishing this task:
  1. Knowing just how often to replace your furnace or air conditioner filter.
  2. Remembering to change air filters when needed.

When To Change Your Air Filters

Most filters have a printed "expiration" date on the box or plastic. It may read "Lasts up to 3 months" or "Change filter every 90 days". Pay attention at the store and you should see that some are meant to only last a single month, while other manufacturers (like Honeywell) have produced media air cleaners with filters meant to be exchanged once every 6-12 months. The industry standard seems to be once every 3 months for most higher quality filters, but we have a rule of thumb that we recommend our readers to go by. If the filter is dirty, change it! A dirty air filter can add or cause damage to expensive components, like your compressor, so it's recommended to change it out more often than not. If you want to stick to the manufacturer's recommended limit, we suggest writing the date on the filter when you swap it out, and adding a reminder for yourself in your phone or on a calendar. Also be aware that your filter manufacturer sometimes has a different recommendation from your HVAC system manufacturer.

Determining how often to change your air filters relies upon several factors:

  • The type of air filter you are using
  • The overall air quality of your Columbia area home
  • Pets – Cats, dogs, birds, etc.
  • Number of occupants in the house
  • How much construction is taking place in the neighborhood around your home

For your typical 1"-3" air filters, the manufacturer specs basically suggest to change them every 30-60 days, which is in fact a great rule of thumb. Still, generalities may not be suitable for your specific needs. If you have to tolerate light to moderate allergies, you might require an upgraded air filter or change them even more frequently than OEM specifications. On the other hand, if you're in a low population area, own a infrequently occupied home (like a vacation home) or an area with little auto traffic, annual replacement of your air filter may be quite sufficient. Why do pets matter so much? They have a tendency to shed, which can clog your air filter in no time, just like a vacuum. Naturally, the air filter is just doing its job by capturing pet hair and dander, but extremely dirty filters can cause seriously reduced HVAC performance.

In summary:

  • Seldom used home or single occupant homes without pets or allergies: Change 6-12 months
  • Typical suburban home without pets: Change every 90 days
  • House with a pet: Change every 60 days
  • More than one pet or have allergies: Change every 30-45 days

How To Remember To Change Your Air Conditioner's Air Filters

Midland Air Service Experts offers a simple solution; sign up for the Service Experts Email Club. This is a convenient way to get money-saving discounts and other helpful information on your smartphone, tablet or desktop. But wait… there’s more, your email subscription preferences let’s you set a reminder to change your Columbia area home's air filter every 30, 60, 90, 120 or 365 days, or any date you find most convenient.

How to replace your return air filter

Most of us know how to replace the air filter in their unit, but some residences have another filter in the return vent. Whether you have one or not is dependent on which HVAC system you have. Your HVAC is designed to handle a maximum amount of pressure in your house, and the more filters you have the more the blower motor works, which can reduce the lifespan of your system if it isn't designed for it. Finding out whether you have a return filter and replacing it is a piece of cake:

  1. Locate your return air vents.
  2. Some covers have screws and some have tabs. Unscrew or pull tabs to remove from the wall.
  3. Check for a filter. If one is in place, pull it out and record the size.
  4. Verify the filter type is the one recommended by the manufacturer.
  5. If filter is dirty, replace with the manufacturer's recommended filter of the same size and type.
Amazing as it may seem, filters can really impact your home's airflow, which is why we recommend referring to the manufacturer. A more expensive HEPA filter that is designed to catch tinier dust will restrict airflow more than a cheaper filter. With restricted airflow comes increased pressure on your system, so you should verify that your HVAC system was made to handle it. Otherwise, you could experience reduced heating and cooling efficiency in your home, and HVAC parts may wear out much faster than the standard.
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