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

February 26, 2015

Need the quick answer? See 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 Dayton area homeowner's can do to protect their air conditioning and heating system between their scheduled tune-ups? It's a simple question with a simple answer; remember to change the heating and air conditioning air filter. Changing 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 among the top five environmental health risks? We know it's the last thing on your mind, but this is really important stuff. Changing the air filters is not a tough thing to do for most Dayton homeowners, but there are often two hurdles to actually completing this job:
  1. Understanding just how often to swap out your furnace or air conditioner filter.
  2. Replacing them at the proper time.

When To Change Your Air Filters

Most filters have a printed "expiration" date on the packaging. It may read "Lasts up to 3 months" or "Change filter every 90 days". Check out the filters at the store and you should see that some are designed to only last one month, while other manufacturers (like Honeywell) have produced media air cleaners with filters meant to be exchanged once every 6-12 months. The 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 pricey equipment, like your compressor, so it's better to change it out more often than not. If you want to follow the manufacturer's recommended limit, we suggest scribbling the date on the filter when you swap it out, and programming a reminder for yourself in your phone or on a calendar. Also note that your filter manufacturer might have a different recommendation from your HVAC system manufacturer.

Deciding how often to change your air filters hinges on several factors:

  • The type of air filter you are using
  • The entire air quality of your Dayton area home
  • Pets – Dogs, cats, 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 OEM specs basically suggest to change them every 30-60 days, which is actually a great rule of thumb. Still, general guidelines are not applicable to all. If you have to tolerate light to moderate allergies, you might need to upgrade your air filter or change them even more regularly than OEM specifications. On the other hand, if you're in a less populated area, own a seldom occupied home (like a vacation home) or an area with few automobiles and trucks, changing your air filter every 12-months may be quite sufficient. Why do pets matter so much? They have a tendency to shed, which can clog your air filter fast. Naturally, the air filter is just doing its job by trapping pet hair and dander, but extremely dirty filters can cause seriously reduced HVAC performance.

In summary:

  • Infrequently occupied home or single occupant homes without pets or allergies: Change 6-12 months
  • Typical suburban home without pets: Change every 90 days
  • Add a dog or cat: 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

It's simple; sign up for the Service Experts Email Club. When you do, you can elect to receive (or not) great email coupons and newsletters with a lot of tips and discounts on AC repairs and tune-ups. Also, your email subscription preferences let’s you set a reminder to change your Dayton area home's air filter every 30, 60, 90, 120 or 365 days, or the date of your choosing.

How to replace your return air filter

Most people know how to replace the air filter in their unit, but some homes have another filter in the return vent. Whether you have one or not is dependent on the HVAC manufacturer's recommendation. Your system is made to handle a set amount of pressure in your house, and the more filters you have the fiercer the blower motor works, which can reduce the life expectancy of your system if it isn't designed for it. Learning whether you have a return filter and replacing it is simple:

  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. Inspect 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.
Crazy as it may seem, filters can dramatically affect your home's airflow, which is why we recommend referring to the manufacturer. A top tier HEPA filter that is designed to catch tinier dust will reduce airflow more than a cheaper filter. With restricted airflow comes more pressure on your system, so you ought to verify that your HVAC system was engineered to handle it. Otherwise, you may experience uneven heating and cooling efficiency in your home, and unit parts may wear out much faster than otherwise.
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