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

February 26, 2015

Occassionally we’re asked what is the number one thing that Austin area homeowner's can do to maintain their air conditioning and heating system between their seasonal tune-ups? Our advice is simple; remember to change the heating and air conditioning air filter. Changing furnace and return air filters is crucial to the proper performance of your HVAC system, as well as your home's air quality. Research suggests that indoor air pollution is in 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 all that hard for most Austin homeowners, but there are usually two obstacles 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 wrapping. It may instruct "Lasts up to 3 months" or "Change filter every 90 days". Pay attention at the store and you'll notice that some are engineered to only last a single month, while other manufacturers (like Honeywell) have created media air cleaners with filters meant to be swapped once every 6-12 months. The standard seems to be once every three months for most higher quality filters, but we have a rule of thumb that we tell our customers to go by. If it's dirty, change it! A dirty air filter can add or cause damage to expensive components, like your compressor, so it's better to change it out more often than neglect it. If you want to follow 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. Also note that your filter manufacturer sometimes has a different recommendation from your HVAC unit manufacturer.

Figuring out how often to change your air filters can depend on several factors:

  • Type of filter your A/C system requires
  • The overall air quality of your Austin area home
  • Pets – Dogs, cats, etc.
  • Number of occupants in the house
  • The level of air pollution and construction around the home

For your typical 1"-3" air filters, the manufacturer specs basically suggest to change them every 1 or 2 months, which is really a great rule of thumb. But general guidelines are not applicable to all. If you put up with 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 remote area, own a infrequently occupied home (like a vacation home) or an area with few automobiles and trucks, 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 quick. Clearly, the air filter is just doing its job by containing pet hair and dander, but exceptionally 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
  • Common suburban home without pets: Change every 90 days
  • Got a cat or dog: Change every 60 days
  • Several 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. 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 Austin 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 you know how to replace the air filter in their equipment, 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 designed to handle a certain amount of pressure in your home sweet home, and the more filters you have the harder the blower motor works, which can shorten the life expectancy of your system if it isn't designed for it. Finding out 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 pull off the wall.
  3. Inspect for a filter. If one is there, 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.
Incredible though it may seem, filters can dramatically impact your home's airflow, which is why we recommend asking the manufacturer. A higher quality HEPA filter that is designed to catch finer dust will obstruct airflow more than a cheaper filter. With restricted airflow comes more 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 unit parts may wear out much faster than the standard.
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