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

February 26, 2015

Every once in a while we’re asked what is the most important thing that North America area homeowner's can do to secure their air conditioning and heating system between their seasonal tune-ups? The answer is simple this; 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, not to mention your home's air quality. Studies show that indoor air pollution is one of 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 North America homeowners, but there are often two obstacles to actually completing this job:

  1. Understanding just how often to change your furnace or air conditioner filter.
  2. Changing them when you’re suppose to.

When To Change Your Air Filters

Most filters have a recommended guideline on the packaging. It may say "Lasts up to 3 months" or "Change filter every 90 days". Check out the filters at the store and you'll see that some are engineered 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 norm seems to be once every few months for most higher quality filters, but we have a rule of thumb that we suggest our friends and family to go by. If the filter is dirty, change it! A dirty air filter can add or cause damage to costly components, like your compressor, so it's recommended to change it out more often than neglect it. 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 be aware that your filter manufacturer might have a different recommendation from your HVAC system manufacturer.

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

  • Type of filter your A/C system requires
  • The overall air quality of your North America area home
  • Pets – Birds, cats, dogs, hamsters (do you have one?), etc.
  • Number of occupants in the house
  • General air pollution in the North America area or construction taking place nearby

For your typical 1"-3" air filters, the manufacturer specs basically say to change them bi-monthly, which is actually a great rule of thumb. However, general guidelines are not applicable to all. If you have to endure light to moderate allergies, you may need to upgrade the 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 infrequently occupied home (like a vacation home) or an area where there are fewer cars around, replacing your air filters each year may be quite sufficient. Why do pets matter so much? They have a tendency to shed, which can clog your air filter fast. Of course, the air filter is just doing its job by capturing pet hair and dander, but tremendously dirty filters can cause diminished 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
  • Add a dog or cat: Change every 60 days
  • Multiple pets or have allergies: Change every 30-45 days

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

Here’s an easy way to stay on top of this; 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. Plus, your email subscription preferences let’s you set a reminder to change your North America 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 houses have an extra filter in the return ductwork. Whether you have one or not is dependent on which HVAC system you have. Your unit is engineered to handle a set amount of pressure in your home sweet home, and the more filters you have the harder the blower motor works, which can decrease the lifespan of your system if it isn't designed for it. Discovering whether you have a return filter and replacing it is easy:

  1. Go to your return air vents.
  2. Some covers have screws and some have tabs. Unscrew or pull tabs to take off the wall.
  3. Inspect for a filter. If one is inside, pull it out and write down 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 alter your home's airflow, which is why we recommend checking in with the manufacturer. A more expensive HEPA filter that is designed to catch smaller debris will reduce airflow more than a cheaper filter. With restricted airflow comes increased pressure on your system, so you need to verify that your HVAC system was built to handle it. Otherwise, you may experience reduced heating and cooling efficiency in your home, and unit parts may die off much faster than normal.
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