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

February 26, 2015

Want the quick 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 Austin area homeowner's can do to ensure efficient functionality of their air conditioning and heating system between their scheduled tune-ups? That’s an easy one; remember to change the heating and air conditioning air filter. Replacing furnace and return air filters is extremely important to the effectiveness of your HVAC system, not to mention 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 Austin homeowners, but there are typically two challenges to actually accomplishing this task:

Determining just how often to replace your furnace or air conditioner filter.
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". Check out the filters at the store and you'll see that some are designed to only last a month, while other manufacturers (like Honeywell) have produced media air cleaners with filters meant to be swapped 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 tell our customers 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 stick to the manufacturer's recommended limit, we suggest marking the date on the filter when you swap it out, and programming 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.

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

Which air filter your system requires
The collective air quality of your Austin area home
Pets – Cats, dogs, birds, etc.
Occupancy of the home
The level of air pollution and construction around the home

For your standard 1"-3" air filters, the manufacturers basically tell you to change them every 30-60 days, which is really a great rule of thumb. Still, general guidelines are not applicable to all. If you suffer from light to moderate allergies, you might need to upgrade your air filter or change them even more frequently than OEM specifications. On the other hand, if you're in a remote area, own a infrequently 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 quick. Clearly, the air filter is just doing its job by containing pet hair and dander, but exceptionally dirty filters can cause weak HVAC performance.

In summary:

Infrequently occupied home or single occupant homes without pets or allergies: Change 6-12 months
Average suburban home without pets: Change every 90 days
Got a cat or dog: 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. In addition, your email subscription preferences let’s you set a reminder to change your Austin 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 system, but some homes have an additional filter in the return ducts. Whether you have one or not is dependent on which HVAC system you have. Your system is made to handle a set amount of pressure in your home, and the more filters you have the more the blower motor works, which can shorten the life of your system if it isn't designed for it. Learning whether you have a return filter and replacing it is a piece of cake:

Locate your return air vents.
Some covers have screws and some have tabs. Unscrew or pull tabs to remove from the wall.
Check for a filter. If one is inside, pull it out and write down the size.
Verify the filter type is the one recommended by the manufacturer.
If filter is dirty, replace with the manufacturer's recommended filter of the same size and type.

Amazing 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 dust will obstruct airflow more than a cheaper filter. With restricted airflow comes greater pressure on your system, so you should verify that your HVAC system was engineered to handle it. Otherwise, you may experience reduced heating and cooling efficiency in your home, and HVAC parts may die off much faster than otherwise.

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