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

February 26, 2015

Want the short 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 Livermore area homeowner's can do to maintain their air conditioning and heating system between their regular 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. Did you know indoor air pollution is in the top five environmental health risks? It’s not thought of often, but it is extremely important to consider. Changing the air filters is not difficult for most Livermore homeowners, but there are typically two obstacles 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 recommended guideline on the packaging. It may read "Lasts up to 3 months" or "Change filter every 90 days". Look around at the store and you should see that some are designed to only last a month, while other manufacturers (like Honeywell) have created media air cleaners with filters meant to be exchanged once every 6-12 months. The standard seems to be once every few months for most higher quality filters, but we have a rule of thumb that we recommend our customers to go by. If it's dirty, change it! A dirty air filter can contribute or cause damage to pricey components, like your compressor, so it's best to change it out more often than to let it go. If you want to listen to the manufacturer's recommended limit, we suggest marking the date on the filter when you swap it out, and adding a reminder for yourself in your phone or on a calendar. Keep in mind that your filter manufacturer might have a different recommendation from your HVAC system manufacturer.

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

  • Which air filter your system requires
  • The overall air quality of your Livermore area home
  • Pets – Birds, cats, dogs, hamsters (do you have one?), etc.
  • Number of people in the home
  • How much construction is taking place in the neighborhood around your home

For the common 1"-3" air filters, the manufacturers basically tell you to change them every 1 or 2 months, which is actually a great rule of thumb. Still, generalities may not be suitable for your specific needs. If you suffer from light to moderate allergies, you might require an upgraded air filter or change them even more often 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, annual replacement of your air filter may be quite sufficient. Why do we call out our beloved pets? They have a tendency to shed, which can clog your air filter in no time, just like a vacuum. Obviously, the air filter is just doing its job by trapping pet hair and dander, but tremendously dirty filters can cause weak HVAC performance.

In summary:

  • Seldom used home or single occupant homes without pets or allergies: Change 6-12 months
  • Common 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. This is a great to receive discounts on service, tips and other helpful information directly to your email. In addition, your email subscription preferences let’s you set a reminder to change your Livermore 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 equipment, but some residences have another filter in the return vent. Whether you have one or not is dependent on the HVAC manufacturer's recommendation. Your system is engineered to handle a maximum amount of pressure in your home sweet home, and the more filters you have the fiercer the blower motor works, which can shorten the life expectancy of your system if it isn't designed for it. Learning whether you have a return filter and replacing it is easy:

  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 note 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 alter your home's airflow, which is why we recommend referring to the manufacturer. A top tier HEPA filter that is designed to catch tinier particles will reduce airflow more than a cheaper filter. With restricted airflow comes more pressure on your system, so you need to verify that your HVAC system was made to handle it. Otherwise, you may experience uneven heating and cooling efficiency in your home, and HVAC parts may wear out much faster than normal.
chat now widget box